500 The American Naturalist. 
RECENT LITERATURE. 
The Woods Holl Lectures.'—It is with pleasure that we 
welcome the second of the series of lectures delivered at the Woods 
Holl Laboratory, for they deserve a larger audience than that for 
which they were especially prepared. In the present volume we have 
ten lectures, each adequately illustrated, most of which are devoted to 
the presentation of the newest thought upon subjects which are most 
prominent in the biological world to-day. They are, moreover, not 
résumés of others’ work but actual contributions to knowledge by orig- 
inal investigators. In his lecture on the “ Mosaic theory of Develop- 
ment,” Professor E. B. Wilson, admitting that the extreme form of 
this theory is untenable, endeavors to show that in a modified shape it 
contains elements of truth, “that we may consistently hold with 
Driesch that the prospective value of a cell may be a function of its 
location and at the same time hold with Roux that the cell has, in 
in some measure, an independent power of self determination due to 
its inherent specific structure.” Professor E. G. Conklin discusses 
certain phenomena in the fertilization of the ovum of Crepidula, a 
form which is especially favorable for the study of the archoplas- 
matic structures, which he maintains are even more important in the 
phenomena of impregnation and mitosis than the nucleus, taking as 
they do the initiative in all the wonderful manifestations of fertiliza- 
tion and cleavage. Further he advances the thesis that the nucleus 
and especially the chromatin is not of necessity the sole bearer of. 
eredity, a position, which if proved to be true, destroys the whole 
fabric of Weismann’s evolution, as at present constituted. í 
_ The third lecture by Professor J acques Loeb, of Chicago University 
1s upon some facts and principles of what he terms physiological mor 
phology. First he deals with heteromorphosis, that is, describes his 
experiments with certain Hydroids, there, by reversing the positions, 
etc., he was able to make roots produce polyps and the free end sa 
grow roots. Next he outlines his experiments with other forms m 
which there was marked polarity. The third subject is the effect upon 
certain forms of a change in the density of sea water, while the fourth 
deals with the production of double and multiple monstrosities in se@ 
urchins, by putting them a short time into diluted sea water and then 
"Biological Lectures delivered at the Marine Biological Laboratory of Woot 
Holl in the summer session of 1893. Boston, 1894. 8°. pp. 242, $2.15. 
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