HEREDITY 547 
ents and offspring, not only the complicated reduction 
divisions involved in the formation of the gametes, but 
also the nuclear and cell-fusions accomplished by the union 
of the egg and sperm in fertilization. . Both processes 
the formation of the gametes, and their fusion offer 
almost unlimited opportunities for alterations of the pro- 
toplasm especially that of the nucleus. This method of 
reproduction, therefore, has the very greatest interest and 
importance for the study of heredity. In the fertilized 
egg 1 are united the inheritances from two parents from 
two distinct lines of ancestry protoplasms (germ-plasms) 
with two entirely different histories extending back into 
the past, no one knows how far. How will these two 
inheritances affect each other when they intermingle in 
the fertilized egg? Will one tend to inhibit or check cer- 
tain characteristics or functions of the other; will they 
evenly blend, so as to produce an expression intermediate 
between that of the parents; or may entirely new sub- 
stances be formed or new combinations take place, result- 
ing in an entirely new expression in the offspring? 
467. Methods of Study. To endeavor to answer the 
questions just asked is as fascinating an occupation as it is 
important, and the answers are significant for man, as well 
as for plants. It is indeed, a fortunate thing that prin- 
ciples ascertained by studying plants apply equally to man 
and other animals, since plants are so much easier to 
handle in experimental investigations. 
We may go about the answering of these questions in 
either of two ways. We may gather large numbers of 
statistics to measure and analyze (statistical or biometrical 
1 The fertilized egg (as Thomson has pointed out) is the inheritance, 
and becomes, in the mature individual, the inheritor. 
