« PreviousContinue »
allowed an ant to visit them, and it immediately seemed by its eager way of running about, to be well aware what a rich flock it had discovered. It then began to play with its antenna; on the abdomen first of one aphis and then of another, and each aphis, as soon as it felt the antenna, immediately lifted up i:s abdomen and excreted a limpid drop of sweet juice, which was eagerly devoured by tho ant. Even tho quite yonng aphides behaved in this manner, showing that the action was instinctive, and not tho result of experience."—Pp. 210, 211.
Or take the following admirable specimen of the union of which we have spoken, of the employment of the observations of others with what he has observed himself, in that which is almost the most marvellous of facts —the slave-making instinct of certain ants. We say nothing at present of the place assigned to these facts in Mr. Darwin's argument, but are merely referring to the collection, observation, and statement of the facts themselves :—
"Slave-making Instinct.—This remarkable instinct was first discovered in tho Formica (Polycrges) rufeseens by Pierre Huber, a better observer even than his celebrated father. This ant is absolutely dependent on its slaves; without their aid the species would certainly become extinct in a single year. Tho males and fertile females do not work. The workers or sterile females, though most energetic and courageous in capturing slaves, do no other work. They are incapable of making their own nests or of feeding their own larva?. When tho old nest is found inconvenient, and they have to migrate, it is tho slaves which determine the migration, and actually carry their masters in their jaws. So utterly helpless are tho masters, that when Huber shut up thirty of them without a slave, but with plenty of the food which they like best, and with their larvat and pupa; to stimulate them to work, they did nothing ; they could not even feed themselves, and many pcrislied of hunger. Huber then introduced a single slave (F. fnsca), and she instantly set to work, fed and saved the survivors, made some cells and tended the larva;, and put all to rights. What can bo more extraordinary than these well-ascertained facts? If we had not known of any other slavemaking ant, it would have been boneless to have speculated how so wonderful an instinct could have been perfected. Another species (Formica sanguinea) was likewise first discovered by P. Huber to bo a slave-making ant. This species is found in the southern parts of England, and its habits have been attended to by Mr. If. Smith, of the British Museum, to whom I am much indebted for information on this and other subjects. Although fully trusting to the statements of Huber and Mr. Smith, I tried to approach the subject in a sceptical frame of mind, as any one may well be excused for doubting the truth of so extraordinary and odious an instinct as that of making slaves. Hence I give
the observations which I have myself made in some little detail. I opened fourteen nests of F. sanguinea, and found a few slaves in each. Hales and fertile females of the slave-species (F. fusca) are found only in their own proper communities, and have never been observed iu the nests of F. sanguinea. The slaves are black, and not nbovo half the size of their red masters, so that the contrast in their appearance is very L;iv.'it. When the nest is slightly disturbed, the slaves occasionally come out, and, lika their masters, are much agitated, and defend the nest. When the nest is much disturbed, and.the larva; and pnpaj are exposed, the slaves work energetically with their masters in carrying them away to a place of safety. Hence it is clear that tho slaves feel quite at home. During the months of June and July, in three successive years, I have watched for many hours several nests in Surrey and Sussex, and never saw n slave cither leave or enter a nest. As, during these months, the slaves are very few in number, I thought that they might behave differently when more numerous, but Mr. Smith informs mo that he has watched nests at various hours during May, June, and August, both in Surrey and Hampshire, and has never seen tho slaves, though present in large numbers in August, cither leave or enter tho nest. Hence lie considers them as strictly household slaves. Tho masters, on the other hand, may bo constantly seen bringing in materials for the nest, and food of all kinds. During the present year, however, in the month of July, I came across a community with an unusually largo stock of slaves, and I observed a few slaves mingled with their masters leaving tho nest, and marching along the same road to a largo Scotch fir-tree, twenty-five yards distant, which they ascended together, probably in search of aphides or cocci. According to Huber, who had ample opportunities for observation, in Switzerland, the slaves habitually work with their masters in making the nest, and they alono open and close the doors'in the morning and evening; and, as Huber expressly states, their principal office is to search for aphides. This difference in tho usual habits of tho masters and slaves in (he two countries probably depends merely on the slaves being captured in greater numbers in Switzerland than in England.
"One day I fortunately witnessed a migration of F. sanguinea from one nest to another, and it was a most interesting spectacle to behold the masters carefully carrying (instead of being carried by, as in the case of lf. rufcsccns) their slaves in their jaws. Another day my attention was struck by about a score of the slave-rankers haunting the same spot, and evidently not in search of food: they approached, and were vigorously repulsed by an independent community of the slave species (F. fusca), sometimes us many as three of these ants clinging to the legs of tho slave-making F. sanguinea. The latter ruthlessly killed their small opponents, and carried their dead bodies as food to their nest, twenty-nine yards distant, but they were- prevented from getting any pupa; to rear »s slaves. I then due up n small parcel of pupa! of F. fusca from another nest, and put them down on a bare spot near the place of combat; they were eagerly seized and carried off by the tyrants, who perhaps fancied that, after all, they had been victorious in their lato combat.
"At the same time I laid on the same place a Email parcel of the pupse of another species (F. II.i v.i), with a few of these little yellow ants still clinging to tho fragments of tho nest. This is sometimes, though rarely, made into slaves, as has been described by Mr. Smith. Although so small a species, it is very courageous, and 1 have seen it ferociously attack other ants. In one instance I found to my surprise an independent community of F. flava under a stone beneath n nest of the slave-making F. stinguinca, and when I had accidentally disturbed both nests, tho little ants attacked their big neighbors with surprising courage.
"Now I was curious to ascertain whether F. sanguinea could distinguish tho pupa; of F. fusca, which they habitually make into slaves, from those of tho little and furious F. flava, which they rarely capture, and it was evident that they did at once distinguish them, for we have seen that they eagerly and instantly seized tho pupa of F. fusca, whereas they were much terrified when they came across the pupa: or even the earth from the nest of F. flava, and quickly ran away; but in about a quarter of an hour, shortly after all the little yellows ants had crawled away, they took heart and carried off the pupa;.
"One evening I visited another community of F. sangninea, and found a numbcrof these nuts returning home and entering their nests, careying tho dead bodies of F. fusca (showing that it was not a migration) and numerous pupa;. I traced a long file of nuts bunhencd with this booty for about forty yards to a very thick clump of heath, whence I saw tho last individual of F. sanguinea emerge, carrying a pupa, but I was not able to find the desolated nest in the thick heath. Tho nest, however, must have been close at hand, for two or three individuals of F. fusca were rushing about in tho greatest agitation, and ono was perched motionless with its own pupa in its mouth on tho top of a spray of heath, an imago of despair over its ravaged home."—P. 219, 223.
Now, all this is, we think, really charming writing. We feel as we walk abroad with Mr. Darwin very much as the favored object of the attention of the dervise must have felt when he had rubbed the ointment around his eye, and had it opened to see all the jewels, and diamonds, and emeralds, and topazes, and rubies, which were sparkling unregarded beneath the earth, hidden as yet from all eyes save those which the dervise had enlightened. But here we are bound to say our pleasure terminates; for when we turn with Mr. Darwin to his " argument," we are almost immediately at variance with him. It is as an "argument" that tho essay is put forward; as an argument we will test it.
We can perhaps best convey to our readers a clear view of Mr. Darwin's chain of reasoning, and of our objections to it, if we set before them, first, the conclusion to which he seeks to bring them ; next, the leading propositions which he must establish in order to make good his final inference; and then the mode by which he endeavors to support his propositions.
The conclusion, then, to which Mr. Darwin would bring us is, that all the various forms of vegetable and animal life with which the globe is now peopled, or of which we find the remains preserved in a fossil state in the great Eorth-Musuem around us, which the science of geology unlocks for our instruction, have come down by natural succession of descent from father to son,—" animals from at most four or five progenitors, and plants from an equal or less number" (p. 484), as Mr. Darwin at first somewhat diffidently suggests; or rather, as, growing bolder when he has once pronounced his theory, he goes on to suggest to us, from one single head :—
"Analogy would lead me one step further, namely, to tlio belief that All Animals and Plants liavo descended from some ono prototype. But analogy may be a deceitful guide. Nevertheless, all living things have much in common in their chemical composition, their germinal vesicles, their cellular structure, and their lawsofgrowth and reproduction. . . . Therefore I should infer from nnalopy that probably all the organic beings which have ever lived on this earth" (man therefore of course included) "have descended from some one primordial form into which life was first breathed by tho Creator."—P. 484.
This is the theory which really pervades the whole volume. Man, beast, creeping thing, and plant of the earth, are all the lineal and direct descendants of some one individual ens, whose various progeny have been simply modified by the action of natural and ascertainable conditions into the multiform aspect of life which we see around us. This is undoubtedly at first sight a somewhat startling conclusion to arrive at. To find that mosses, grasses, turnips, oaks, worms, and flies, mites and elephants, infusoria and whales, tadpoles of to-day and venerable saurians, truffles and men, are all equally the lineal descendants of the same aboriginal common ancestor, perhaps of the nucleated cell of some primaeval fungus, which alone possessed the distinguishing honor of being the "one primordial form into which life was first breathed by the Creator"—this, to say the least of it, is no common discovery—no very expected conclusion. But we are too loyal pupils of inductive philosophy to start back from any conclusion by reason of its strangeness. Newton's patient philosophy taught him to find in the falling apple the law which governs the silent movements of the stars in their courses; and if Mr. Darwin can with the same correctness of reasoning demonstrate to us our fungular descent, we shall dismiss our pride, and avow, with the characteristic humility of philosophy, our unsuspected cousinship with the mushrooms,;—
"Claim kindred there, and have our claim allowed,"
—only we shall ask leave to scrutinize carefully every step of the argument which has such an ending, and demur if at any point of it we are invited to substitute unlimited hypothesis for patient observation, or the spasmodic fluttering flight of fancy for the severe conclusions to which logical accuracy of reasoning has led the way.
Now, the main propositions by which Mr. IJarwin's conclusion is attained are these:—
"1. That observed and admitted variations spring up in the course of descents from a common progenitor.
"2. That many of these variations tend to an improvement upon the parent stock.
"3. That, by a continued selection of these improved specimens as the progenitors of future stock, its powers may be unlimitedly increased.
"4. And, lastly, that there is in nature a power continually and universally working out this selection, and so fixing and augmenting these improvements."
Mr. Darwin's whole theory rests upon the truth of these propositions, and crumbles utterly away if only one of them fail him. These therefore we must closely scrutinize. We will begin with the last in our series, both because we think it the newest and the most ingenious part of Mr. Darwin's whole argument, and also because, whilst we absolutely deny the mode in which ho seeks to apply the existence of the power to help him in his argument, yet we think that he throws great and very interesting light upon the fact that such a self-acting power does actively and continuously work in all creation around us.
Mr. Darwin finds then the disseminating and improving power, which he needs to account for the development of new forms in nature, in the principle of" Natural Selection," which is evolved in the strife for room to live and flourish which is evermore maintained between themselves by all living things. One of the most interesting parts of Mr. Darwin's volume is that in which he establishes this law of natural selection; we say establishes, because—repeating that we differ from him totally in the limits which he would assign to its action—we have no doubt of the existence or of the importance of the law itself. Mr. Darwin illustrates it thus:—
"There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the offspring of a single pair. Linntcus has calculated that if an annual plant produced only two seeds—and there is no plant so unproductive as this—and their seedlings next year produced two, and so on, then in twenty yeiys there would bo a million plants. The elephant is reckoned the slowest breeder of all known animals, and I have taken some pains to estimate its probable minimum rate of natural increase. It will be under tho mark to assume that it breeds when thirty years old, and goes on breeding till ninety years old, bringing forth three pair of young in this interval; if this be so, at the end of the fifth century there would bo alivo fifteen million elephants, descended from the first pair."—P. 64.
Leaving theoretical calculations, Mr. Darwin proceeds to facts to establish this rapid increase:—
"Several of the plants, such as the cardoon, and a tall thistle, now most numerous over the wide plains of La Plata, clothing square leagues of surface almost to the exclusion of all other plants, have been introduced from Europe."— P. 65.
And, again, he reasons from the auimal world:—
"Tho condor lays a couple of eggs and tho ostrich a score, and" yet in the same country tho condor may bo the more numerous of the two. Tho fulmar petrel lays but one egg, yet it is believed to be tho most numerous bird in the world."—P. 66.
This is followed by a passage which well illustrates the care and cleverness of Mr. Darwin's own observations:—
"On ft piece of ground three feet long and two wide, dug and cleaned, nnd where there could bo no choking from other plants, I marked all the seedlings of our native weeds as they came up, and, out of the three hundred and fiftyseven, no less than two hundred and ninety-fire vrero destroyed, chiefly by slugs and insects. If turf which has long been mown—and the case •would be the same with turf closely browsed by quadrupeds—lie let to grow, the more vigorous plants gradually kill the less vigorous though fully grown plants; thus out of twenty species growing on a little plot of turf (three feet by four) nine species perished from the other species being allowed to grow up freely."—Pp. 67, 68.
Now all this is excellent. The facts are all gathered from a true observation of nature, and from a patiently obtained comprehension of their undoubted- and unquestionable relative significance. That such a struggle for life then actually exists, and that it tends continually to lead the strong to exterminate the weak, we readily admit; and in this law we sec a merciful provision against the deterioration, in a world apt to deteriorate, of the works of the Creator's hands. Thus it is that the bloody strifes of the males of all wild animals tend to maintain the vigor and full development of their race j because, through this machinery of appetite and passion, the most vigorous individuals become the progenitors of the next generation of the tribe. And this law, which thus maintains through the struggle of individuals the high type of the family, tends continually, through a similar struggle of species, to lead the stronger species to supplant the weaker.
This, indeed, is no new observation: Lucretius knew and eloquently expatiated on iU truth:—
"Multaqne turn interiisse animantum sccln ne
Nee potnisso propagando procudere prolcm. Nam, quxcumquo vidcs vcsci vitalibus nuris Aut dolus, aut virtus, aut deniquo mobilitas,
est, Ex incuntc tevo, genus id tutata reservant." *
And this, which is true in animal, is no less true in vegetable life. Hardier or more prolific plants, or plants better suited to the soil or conditions of climate, continually tend to supplant others less hardy, less prolific, or less suited to the conditions of vegetable life in those special districts. Thus far, then, the action of such a law as this is clear and indisputable.
But before we can go a step further, and argue from its operation in favor of a perpetual improvement in natural types, we must be shown first that this law of compc* Lucret., " Do Her. Nat," lib. v.
tition has in nature to deal with such favorable variations in the individuals of any species, as truly to exalt those individuals above the highest type of perfection to which their least imperfect predecessors attained—above, that is to say, the normal level of the species ;—that such individual improvement is, in truth, a rising above the highest level of any former tide, and not merely the return in its appointed season of the feebler neap to the fuller spring-tide;—and then, next, we must be shown that there is actively at work in nature, co-ordinate with the law of competition and with the existence of such favorable variations, a power of accumulating such favorable variation through successive descents. Failing the establishment of either of these last two propositions, Mr. Darwin's whole theory falls to pieces. He has accordingly labored with all his strength to establish these, and into that attempt we must now follow him.
Mr. Darwin begins by endeavoring to prove that such variations are produced under the selecting power of man amongst domestic animals. Now here we demur in limine. Mr. Darn-in himself allows that there is a plastic habit amongst domesticated animals which is not found amongst them when in a state of nature. "Under domestication, it may be truly said that the whole organization becomes in some degree plastic." (P. 80.) If so, it is not fair to argue, from the variations of the plastic nature, as to what he himself admits is the far more rigid nature of the undomesticated animal. But we are ready to give Mr. Darwin this point, and to join issue with him on the variations which he is able to adduce, as having been produced under circumstances the most favorable to change. He takes for this purpose the domestic pigeon, the most favorable specimen no doubt, for many reasons, which he could select, as being a race eminently subject to variation, the variations of which have been most carefully observed by breeders, and which, having been for some four thousand years domesticated, affords the longest possible period for the accumulation of variations. But with all this in his favor, what is he able to show? He writes a delightful chapter upon pigeons. Runts and fantails, short-faced tumblers and long-faced tumblers, long-beaked carriers and pouters, black barbs, jacobins, and turbits, coo and tumble, inflate their oesophagi, and pout and spread out their tails before • us. We learn that "pigeons have been •watched and tended with the utmost care, and loved by many people." They have been domesticated for thousands of years in several quarters of the world. The earliest known record of pigeons is in the fifth Egyptian dynasty, about three thousand years B.C., though " pigeons are given in a bill of fare " (what an autograph would be that of the chef-de-cuisine of the day!) "in the previous dynasty " (pp. 27, 28): and so we follow pigeons on down to the days of " that most skilful breeder Sir John Sebright," •who "used to say, with respect to pigeons, that 'he would produce any given feather in three years, but it would take him sis years to produce beak and head.'"—P. 31.
Now all this is very pleasant writing, especially for pigeon-fanciers; but what step do we really gain in it at all towards establishing the alleged fact that variations are but species in the act of formation, or in establishing Mr. Darwin's position that a wellmarked variety may be called an incipient species? We affirm positively that no single fact tending even in that direction is brought forward. On the contrary, every one points distinctly towards the opposite conclusion; for with all the change wrought in appearance, with all the apparent variation in manners, there is not the faintest beginning of any such change in what that great comparative anatomist, Professor Owen, calls "the characteristics of the skeleton or other parts of the frame upon which specific differences are founded." * There is no tendency to that great law of sterility which, in spite of Mr. Darwin, we affirm ever to mark the hybrid; for every variety of pigeon, and the descendants of every such mixture, breed as freely, and with as great fertility, as the original pair; nor is there the very first appearance of that power of accumulating variations until they grow into specific differences, which is essential to the argument for the transmutation of species; for as Mr. Darwin allows, sudden returns in color, and other most altered appearances, to the parent stock continually attest the tendency of variations not to become fixed, but to vanish, and manifest the perpetual presence of a principle leading not to the accumulation of minute
* " On the Classification or Mammalia," p. 98.
variations into well-marked species, but to a return from the abnormal to the original type. So clear is this, that it is well known that any relaxation in the breeder's care effaces all the established points of difference, and the fancy-pigeon reverts again to the character of its simplest ancestor.
The same relapse may moreover be traced in still wider instances. There are many testimonies to the fact that domesticated animals, removed from the care and tending of man, lose rapidly the peculiar variations which domestication had introduced amongst them, and relapse into their old untamed condition. "Plus," says M. P. S. Pallas,* "je reflechis, plus je suis dispose a croire que la race des chevaux sauvages que 1'on trouve dans les landes baignees par le Jaik et le Don, et dans cellos de Baraba, ne provient que de chevaux Kirguis ct Kalmouks devenus sauvages," etc.; and he proceeds to show how far they have relapsed from the typo of tame into that of wild horses. Prichard, in his " Natural History of Man," remarks that the present state of the escaped domesticated animals, which, since the discovery of the Western Continent by the Spaniards, have been transported from Europe to America, gives us an opportunity of seeing how soon the relapse may become almost complete. "Many of these races have multiplied (he says) exceedingly on a soil and under a climate congenial to their nature. Several of them havo run wild in the vast forests of America, and have lost all the most obvious appearances of domestication.''f This he proceeds to prove to be more or less the case as to the hog, the horse, the ass, the sheep, the goat, the cow, the dog, the cat, and gallinaceous fowls.
Now, in all these instances we have the result of the power of selection exercised on the most favorable species for a very long period of time, in a race of that peculiarly plastic habit which is the result of long domestication; and that result is, to prove that there has been no commencement of any such mutation as could, if it was infinitely prolonged, become really a specific change.
There is another race of animals which comes under our closest inspection, which has been the friend and companion of man
* " Voyages de M. P. S. Pnllas, tradnit de VAllemand par M. Ganltierdo In Pcyroune," vol. i. p. 89. t " Natural History of Man," pp. 27, 28.