"Heaven forfend me from Lamarck nonsense of a tendency to progression, adaptations from the slow willing of animals, etc.; but the conclusions I am led to are not widely different from his; though the means of change are wholly so. I think I have found out (here's presumption!) the simple way by which species become exquisitely adapted to various ends."— C. DARWIN to J. D. HOOKER, Jan. 11, 1848. "The hypothesis of Lamarck - that progressive changes in species have been produced by the attempts of animals to increase the development of their own organs, and thus to modify their structure and habits has been repeatedly and easily refuted by all writers on the subject."— WALLACE: " 'On the Tendency of Varieties to depart indefinitely from the Original Type," Journ. Proc. Linnean Soc.," August, 1858. "The Lamarckian hypothesis has long since been justly condemned."- HUXLEY: "Collected Essays," II., p. 12, 1859. "It may be doubted whether Lamarck has not suffered more from his friends than from his foes."- HUXLEY: "Collected Essays," II., p. 69. "Lamarck assigned partly unreal, partly insufficient causes; and the attempt to account for a progressive change in species through the direct influence of physical agencies, and through the appetencies and habits of animals reacting upon their structure, thus causing the production and the successive modification of organs, is a conIceded and total failure.". ASA GRAY: "The Origin of Species by Means of Natural Selection," Amer. Journal Science and Arts, March, 1860. LECTURE IV LAMARCK CONCLUSIVE proof of the inheritance of the effects of the direct action of the conditions of life may be found at any moment, for all one knows to the contrary; but even if they who are acquainted with no positive evidence think, with the writer, that a dogmatic assertion, from negative evidence, or in the absence of all evidence, that these effects are not inherited, or cannot be inherited, would be rash and unscientific, they may, nevertheless, be interested in an attempt to test the value of the assumption that they are inherited; admitting, in the interest of clear thinking, that the assumption is reasonable and admissible. That "inheritance of acquired characters" might produce some system of living nature seems probable; if we start with organisms with such constitution that this "factor" tends to produce modifications which are both adaptive and inherited. That it has not produced, or materially aided in producing, the system which we know seems certain. Our business is to study that which is, not that which might be; and I shall try to show, as it has been shown again and again, that the adjustments which are exhibited by living things are such as to show that the "inheritance of acquired characters" has played no essential part in their production. The most extreme Lamarckian must admit that no organism can transmit or inherit modifications produced by the conditions of any life except its own, or that of its ancestors. The nurture of A cannot be transmitted by B; nor can it be part of the inherited nature of B's descendants unless they are also descended from A. How, then, are we to explain such things as the bee's sting or the poison of serpents, - things which are useful only in their effect on other animals than the user? How are we to explain adjustments to the life of other beings. than the ones that exhibit the adjustment? As the serpent which is able to destroy its prey, and the bee which is able to drive away its enemies, have an advantage in the struggle for existence, it is easy to understand how these powers may have arisen through selection; for the bee's sting is a modified ovipositor, and it is used by some of the Hymenoptera both as a weapon of defence, and as an organ for laying the eggs in the tissues of plants, thus exciting pathological changes in these tissues, so that they form galls, and store up, around the eggs, starch to serve as food for the larvae which hatch from the eggs. While the origin of these adjustments by selection is quite intelligible, there does not seem to be any other way to account for them. The white upturned tail of the rabbit is a danger-signal. When disturbed or alarmed on the feeding-ground, which they visit soon. after sunset or on moonlight nights, the rabbits make for their burrows, and the white upturned tails of those in front serve as guides and signals to those more remote from home, to the young and feeble; and thus, each following the one or two before it, all are able, with the least possible delay, to reach a place of safety. Many defenceless insects are protected by their resemblance to dangerous animals, or by some threatening or unusual appearance. The great green caterpillar, known in some of our Southern states as the "hickory-horned devil," has an immense crown of orangered tentacles, which, if disturbed, it erects and shakes from side to side in a manner so alarming that the negroes believe it is more deadly than a rattlesnake. Who can believe that the inherited effect of the terror it excites has modified the hickory-horned devil? After giving the matter my best and most serious thought, I am unable to imagine any way in which the effect of the upturned tail of the hinder rabbit can act upon the tail of the rabbit in front, or any way by which the sight of the tail in front can modify the tail of the rabbit behind. I find the production of adaptations of this sort by the inheritance of the beneficial effects of use, or in any way except by selection, quite unthinkable. Most pelagic larvæ are transparent, even when the 1 |