542 The American Naturalist. [July, 
the germ-cells by the circulation of minute buds from each 
cell; each body-cell throws off a “ gemmule” containing its 
characteristics; these gemmules multiply and become espec- 
ially concentrated in the germ-cells; in the latter they unite 
with others like themselves; in course of development they 
grow into cells like those from which they were originally 
given off. (See Diagram II.) 
Galton} who has always been doubtful in regard to use- 
inheritance, while advancing a theory of “ continuity,” partly 
approved Darwin’s pangenesis idea in the cautious statement : 
“ Each cell may throw off a few germs that find their way 
into the circulation and thereby have a chance of entering 
the germ-cells.” At the same time Galton contributed very 
important experimental disproof of the existence of “gemmules,” 
and, in fact, of the popular idea, of the circulation of heredi- 
tary characters in the blood, by a series of careful experiments 
upon the transfusion of blood in rabbits; he found that the 
blood did not convey with it even the slightest tendency to 
transfer normal characteristics from one variety to another. 
Professor Brooks? of the Johns Hopkins University, then 
contributed an original modification of pangenesis in which 
the functions of the ova and spermatozoa were sharply differ- 
entiated. (1) He regarded the ovum as a cell especially 
designed as a storehouse of hereditary characteristics, each 
characteristic being represented by material particles of some 
kind; thus hereditary characters were handed down by sim- 
ple cell division, each fertilized ovum giving rise to the body- 
cells in which its hereditary characters were manifested and 
to new ova in which these characters were conserved for the 
next generation (this portion of Brooks’s theory is very sim- 
ilar to Galton’s and Weismann’s). 2. The body-cells have the 
power of throwing off “gemmules,” but this is exercised 
mainly or exclusively when its normal functions are disturbed, 
as in metatrophic exercise or under change of environment. 
3. These gemmules may enter the ovum, but the spermato- 
zoan is their main center. According to this view the female 
1Contemporary Review, vol. xxvii., p. 80-95. 
2The Law of Heredity, 1883. 
