ing factor, and it is perfectly natural that certain less plastic individuals should, through the influence of heredity, continue loyal to the British standard; for the tendencies toward the establishment of a new type are not the result of the selection of the fit nor the elimination of the unfit, but, rather, the result of a direct influence upon all.

The questions remain to be answered: Are the new variations the result of the influence of the environment reiterated in the case of each particular individual, or has the mechanism of heredity been affected so that the American birds are producing new eggs through its directive influence? Has "Buffon's factor" (Osborn, '94), the direct action of environment, produced definite and adaptive variations which are merely "contemporary individual differences" (Cunningham, '93), or are these variations approved and adopted as a part of the constitution of a phyletic series? In brief, is the new variety merely ontogenic, or is it phylogenic?

The maturating as well as the developing ovum must be looked upon as an organism, and "as such must dominate its own development" (Whitman, '94). The ovarian ovum gathers to and about itself certain constituent parts and incorporates them according to its individual peculiarities. As it leaves the ovary, laden with yolk, it gathers about itself the envelopes of albumen, shell-membrane, and shell which it is the function of the oviducal walls to secrete. To assume that the organized ovum has no control, exercises no influence over the development and arrangement of these secondary envelopes, is like assuming that the presence of an ovum in the mammalian uterus exercises no influence upon the uterine walls. But the material submitted to the ovum by the somatic cells is not necessarily always qualitatively and quantitatively the same, and, on the other hand, there is no reason to suppose that any two ova, even of the same parent, have precisely the same peculiarities. The entire bird's egg is the result of the centrifugal influence of the ovum exerted upon the surrounding tissue no less than the centripetal influence of the surrounding tissues exerted upon the ovum; of the keimplasm exerted upon the soma no less than of the soma exerted upon the keimplasm, and, in

dealing with a portion of the resulting structure, viz., the shell, we are dealing perhaps somewhat more directly with the influence of heredity and its vehicle than we would be, if the subject of our discussion were a more distant somatic product, such as a bone or a feather.

The relation of the ovum to the complete egg is practically the same as that of a "caddis-worm," to its "case." The preferred material may be bits of straw, but, in the absence of straw, small pieces of wood may be made to answer. The "worms" in the "cases" of wood are themselves not different from their, perhaps more fortunate, neighbors in straw "cases." It is only when they adopt the wood in preference to the straw that an ontogenic makeshift becomes a phylogenic variation. New building material does not make a new architect.

In America the materials supplied for the developing ovum are different from those supplied in England, and the resulting structure is consequently different. To what extent the new materials have won the favor of the keimplasm cannot be determined by merely allowing American birds to breed again in England, for in England there would be a prejudice in favor of local material, and under the revival of an ancient environment palingenic variation might also deceive. Both English and American birds should be placed in some third locality which combines equally or eliminates the prejudicial environmental conditions of the two countries. Then, and not until then, shall we know to what extent the ontogenic variations in either country have really become phylogenic.

REFERENCES.

'72. DARWIN, CHARLES. The Origin of Species by Means of Natural Selection. (Sixth edition.)

"74. ROMANES, GEO. J. Nature. Vols. ix and x.

'83. WEISMANN, AUGUST. Inaugural Lecture as Pro-Rector of the University of Freiburg. (Reprinted in '89 as the second of the "Essays.")

'89. WEISMANN, AUGUST. Essays upon Heredity and Kindred Biological Problems. Oxford.

'89. MERRIAM, C. HART, and BARROWS, WALTER B. The English Sparrow in North America. United States Department of Agriculture. (Division of Economic Ornithology and Mammalogy, Bulletin I.)

'90. ROMANES, GEO. J. Panmixia. Nature. Vol. xli.

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LANKESTER, E. RAY. The Transmission of Acquired Characters,
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'94. SCOTT, W. B. On Variations and Mutations. Am. Jour. Sci. Vol.

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'94. WHITMAN, C. O. Evolution and Epigenesis. Biological Lectures. (Wood's Holl.)

'94. OSBORN, H. F.

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'95. ROMANES, GEO. J. Post-Darwinian Questions, Heredity and Utility.

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96. COPE, E. D. The Primary Factors of Organic Evolution. Chicago. '97. BUMPUS, H. C. A Contribution to the Study of Variation. Journal of Morphology. Vol. xii.