642 The American Naturalist. [August, 
HEREDITY AND THE GERM-CELLS. 
By Henry FAIRFIELD OSBORN. 
THe CARTWRIGHT LECTURES ror 1892, III. 
(Continued from Page 567, Vol. XXVI) 
According to the general law' the germ-cell is considered 
as matter potentially alive and having within itself the ten- 
dency to assume a definite living form in course of individual 
development. The nucleus must be extraordinarily complex, 
for it contains within itself not only the tendencies of the 
present type, but of past types far distant. The supposition 
of a vast number of germs of structure is required by the phe- 
nomena of heredity ; Niigeli has demonstrated that even in so 
minute a space as ry; cub. millimetre, 400,000,000 micelle 
must be present. 
The study of heredity will ultimately centre around the 
structure and functions of the germ-cells. The precise 
researches of Galton show that the external facts of heredity, 
questions of averages and of probabilities, of paternal and 
maternal contributions to the offspring, are capable of being 
reduced to an exact science in which mathematical calcula- 
tions will enable us to forecast the characteristics of the coming 
generation. 
There will still remain, however, a large residuum of facts 
which will present themselves to a mathematician like Galton 
as chance or inexact, such as the physiological conditions of 
reversion; the causes of prepotency, by which the maternal 
or the paternal characteristics prevail in parts or in the entire 
structure of the offspring; the material basis of latent heri- 
tage upon which reversion depends, and which compels us to 
hypothecate either an unused hereditary substance or a return 
to an older disposition of the forces in this substance; the 
nature and determination of sex. These apparently chance 
See Huxley, Article Evolution, Enc. Britannica, p. 746. 
