REVIEWS OF RECENT LITERATURE. 
GENERAL BIOLOGY. 
The Specialized Nature of Cells..— The author brings facts, 
largely from the medical literature, to support his modification of 
Virchow’s famous dictum, so that it reads: Omnis cellula e cellula 
cjusdem nature. In the first chapter he discusses the relative claims 
of the theories of the indifferent nature and the specialized nature 
of cells in the body. Next he considers the hereditary fixity of cell- 
types in adult organisms, and attempts to show that all conclusions 
that in pathology or regeneration the organs of new growths arise 
from other than like cells in the body, rest upon erroneous interpre- 
tation. Unfortunately many of the best cases supporting the view 
he combats (such as Wolff’s case of the regeneration of the Amphib- 
ian lens) are not considered bythe author. The third chapter deals 
with the origin of specialization of cells during development, which 
he believes comes in with the germ-layers. Finally cell specialization 
is considered from the standpoint of life and heredity. 
Although one-sided and speculative, the book has a value as giv- 
ing the point of view of a medical man. 
Sex.? — This small book, by the well-known French writer on top- 
ics of a general biological nature, gives a résumé of the general facts 
of sexual dimorphism, parthenogenesis, the dependence of the sec- 
ondary sexual characters on the primary, the epoch and conditions 
of sex-determination, and the theory of sex. In the chapter dealing 
with secondary sexual characters the author considers sexual selec- 
tion, the results of castration, and the phenomena of hermaphroditism. 
Other chapters are treated with equal fullness. 
The author proposes a hypothesis of sex which he admits is very 
uncertain. It is that all the elementary living substances have two 
inverse and complementary types; just as many inorganic molecules 
appear in two forms. One of these types is the male; the other the 
female type. 
1 Bard, L. La Spécificité Cellulaire, ses consequences en biologie générale, 
Scientia, Sér. Biologie, No. r. Paris, Carré & Naud, 1 98 pp. 
2 Le Dantec, F. La Sexualité, Scientia, Sér. Sistapiaed No.2. Paris, Carré & 
Naud. 99 pp. a 
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