332 SIRKS, PRAE-MENDELISTISCHE ERFELIJKHEIDSTHEORIEEN. 
ctions of the two elements are alike, and the union of parts 
derived from the bodies of two parents simply insures variability 
in the offspring. 
„In all multicellular organisms the ovum and the male cell have : 
gradually become specialized in different directions. 
„Ihe ovum is a cell which has gradually acquired a compli- 
cated organization, and which contains material particles of some 
kind to correspond to each of the hereditary characteristics of the 
species. 
„Ihe ovum, like other cells, is able to reproduce its like, and 
it not only gives rise during its development to the divergent 
cells of the organism, but also to cells like itself. 
„Ihe ovarian ova of the offspring are these latter cells, or their 
direct unmodified descendants. 
„Each cell of the body is, in a morphological sense, an inde- 
pendent individual. It has the power to grow, to give rise by divi- 
sion to similar cells, and to throw off minute germs. During the 
evolution of the species it has by natural selection acquired dis- 
tinctive properties or functions, which are adapted to the condi- 
tions under which it is placed. So long as these conditions remain 
unchanged it performs its proper function as a part of the body; 
but when, through a change in its environment, its function is 
disturbed and its conditions of life become unfavorable, it throws 
off small particles which are the germs or ,,gemmules” of this 
particular cell. 
„Ihese germs may be carried to all parts of the body. They 
may penetrate to an ovarian ovum or to a bud, but the male cell 
has gradually acquired, as its especial and distinctive function, a 
peculiar power to gather and store up germs. 
„When the ovum is fertilized each germ or „gemmule” unites 
with, conjugates with, or impregnates, that particle of the ovum 
which is destined to give rise in the offspring to the cell which 
corresponds to the one which produced the germ or gemmule; or 
else it unites with a closely related particle, destined to give rise 
to a closely related cell. 
» When this cell becomes developed in the body of the offspring 
it will be a hybrid, and it will therefore tend to vary. 
„As the ovarian ova of the offspring share by direct inheritance 
