No. 397.] REVIEWS OF RECENT LITERATURE. 57 
problems of the day. The opening lecture is on the structure of 
protoplasm, by E. B. Wilson, whose study of the living echinoderm 
egg has led him to revise his former opinion and declare himself now 
in favor of the alveolar structure of protoplasm. Too much stress 
cannot be laid upon the importance which the author ascribes to the 
study of living protoplasm as a check upon what we assume to be 
a satisfactory preservation of it by histological means. Five lectures 
deal with problems of celllineage: the homologies of cells and cell 
groups are discussed by E. B. Wilson; the interpretation of the vari-_ 
ous kinds of egg cleavage as adaptations of the egg is taken up by 
F. R. Lillie; the importance of protoplasmic movement in the distri- 
bution of materials from the nucleus is emphasized by E. G. Conklin; 
equal and unequal cleavage in annelids is treated by A. L. Treadwell, 
who points out that those organs which appear early in ontogeny are 
usually represented by large-bodied cells, irrespective of the distribu- 
tion of yolk; the origin of the prototroch is considered by A. D. Mead. 
Closely related to these subjects are C. M. Clapp's lecture on the rela- 
tion of the axis of the embryo to the first cleavage plane, which is 
dealt with from the modern experimental standpoint, and T. H. Mont- 
gomery's account of the nucleolus. The possible relations of con- 
tractility and phosphorescence are pointed out by S. Watasé, who 
argues for the view that phosphorescence may be a general property 
of living protoplasm. T. H. Morgan, in considering some of the 
problems of regeneration, points out the apparent inefficiency of 
purely mechanical explanations, and suggests to students the impor- 
tance of keeping the vitalistic standpoint in view. Problems in evo- 
lution are represented by H. C. Bumpus's interesting examination of 
a large number of English sparrows killed in a severe winter storm ; 
the birds eliminated were in one respect or another far removed from 
the typical form. The question of heredity is dealt with by J. Loeb, 
as illustrated in the markings of fish embryos, and the present neces- 
sity of an analytic treatment is enforced. Paleontology is represented 
by W. B. Scott’s account of North American ruminant-like mammals. 
An appreciative historical review of Wolff's Zheoria generationis is 
given by W. M. Wheeler. Animal psycho-physiology is represented 
by W. W. Norman's very interesting paper on the question whether 
the reactions of lower animals due to injury indicate sensations of 
pain, and C. O. Whitman’s elaborate account of the habits oí 
leeches, salamanders, and pigeons. The volume is concluded with 
brief memorial notices of J. I. Peck, J. E. Humphrey, and W. W. 
Tom. G. H. P. 
