possessing in a measure the same characters. Nevertheless, the transmission of individual environmental adaptations has been established.

No cases of the transmission of functional adaptations as unquestionable as those of environmental adaptations are on record.

It has seemed difficult indeed to devise experiments which would prove that the small somatic changes possible during a lifetime are transmitted. We were not sanguine enough to suppose that in one generation modifications could be effected and transmitted that would surpass natural variability, and which could, therefore, be recognized as transmitted characters. I have long been convinced that the progressive degeneration of the eyes of cave vertebrates, coupled with the differential degeneration of different parts, is due and can be due to nothing but the transmission of functional adaptation. I can not altogether regret that this evidence does not seem to have convinced many others.

The possibility of the transmission of somatic characters to the reproductive cells has been shown by the transplantation of ovaries in chicks by Guthrie. He found that a black hen containing an ovary transplanted from a white hen, mated with a white male, did not give white chicks exclusively, as the non-transmissibility of somatic characters would require, but that more than half of the chicks were spotted with black. Also that a white hen containing an ovary trans

planted from a black hen and mated with a black male gave young all of which were spotted. These results, if based on rigorously selected material, ought to convince all but a packed jury that somatic characters are transmissible to the reproductive cells. If any one knows of defects in Guthrie's material it is incumbent on him to furnish or define material free from all objections on which his experiments may be repeated; for the method promises a final answer to this much debated question.

H. CONCLUSIONS. We are forced to the inevitable conclusions that adaptations are not chargeable to one factor, but that sometimes there has been one, sometimes another, and more frequently several factors have coöperated to bring about the adaptations in any one animal.

It is but justice to Darwin to say that he did not pin his faith to the theory of Natural Selection exclusively. Darwinism is broader than neo-Darwinism, whose insufficiency to account for all adaptations becomes daily more apparent.

After fifty years of study of the origin of adaptations a single sentence from Darwin's Origin of Species approaches closely to the general conclusions of to-day, and, "lest we forget," it should be emblazoned on the walls of every Biological Laboratory: "These laws, taken in the largest sense, (are) growth, with reproduction; inheritance, which is almost implied by reproduction; variability, from the indirect and

direct action of the external conditions of life, and from use and disuse; a rate of increase so high as to lead to a struggle for life, and as a consequence Natural Selection entailing divergence of characters and the extinction of less improved forms."

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I. A PLEA FOR THE NATURALIST. I can not close this paper without a plea for the naturalist and systematic zoölogist. Analysis," says Ruskin, "is an abominable business. I am quite sure that people who work out subjects thoroughly are disagreeable wretches. One only feels as one should when one doesn't know much about the matter."

The systematic zoölogist is liable to lose sight of the woods on account of the trees, and follow the example of Jean Paul Richter's Quintus Fixlein, who collected a vast number of typographical errors, assured the public that valuable conclusions could be drawn from them, and left it to some one to draw them.

The imagination is in Biology as elsewhere the guiding spirit. The trouble is our imaginations are sometimes too heavily loaded with statistics and at other times they fly without the balancing kite's tail of facts. The Paleontologists have contributed so much to speculative zoölogy because their imaginations have been kept alive by bridging their numerous gaps and because they have not been hampered by too great a wealth of material.

Whether we amputate eyes and legs to see them regenerate, determine the chromosomic differences between related species, centrifuge eggs, or invent new plants, potato beetles, guinea-pigs, or poultry, match butterflies, count scales, or measure fossils, we are all at work on the problem of problems, "The origin of adaptations.'

Experiment is the watchword of the day; but while we are experimenting in our back yards we should not lose sight of the beauty and the importance of the experiments in landscape gardening and zoological gardening, that are and have been going on in our front yards that extend from here to Cape Horn.

6

DARWIN AND PALEONTOLOGY

BY

HENRY FAIRFIELD OSBORN

ON March 4, 1860, Charles Darwin wrote1 to Joseph Leidy of Philadelphia:

"Your note has pleased me more than you could readily believe; for I have during a long time heard all good judges speak of your paleontological labours in terms of the highest respect. Most paleontologists (with some few good exceptions) entirely despise my work, consequently approbation from you has gratified me much; all the older geologists with the one exception of Lyell, whom I look at as a host in himself, are even more vehement against the modification of species than are even the paleontologists. I have, however, been equally surprised and pleased at finding that several of the younger geologists, who are now doing such good work in our own geological survey go with me and are as strong as I can be on the imperfections of geological record.

"Your sentence that you have some interesting facts. in support of the doctrine of selection, which I shall

1 Darwin's letter to Dr. Leidy is under date of March 4, 1860, in reply, as he states, to Leidy's letter of December 10, 1859.

On March 27, 1860, upon the recommendation of Isaac C. Lea and Dr. Joseph Leidy, Darwin was elected a corresponding member of the Philadelphia Academy of Natural Sciences. It is probable that to the Philadelphia Academy belongs the honor of having been the first foreign society to accord this great work official recognition. This recognition was appreciated by Darwin, as is shown by his reference to it in a letter to Sir Charles Lyell, dated May 8, 1860.

The original letter is in the collection of Dr. Joseph Leidy of Philadelphia, nephew of the great anatomist.