THE GERM-PLASM THEORY 309 
sults of hybridization. Thus if the position of a 
newly discovered factor is determined by comparison 
with another particular known factor, it is possible 
to “‘calculate the results for all other known factors 
in the same chromosome.” Morgan’s ideas regard- 
ing the organization of the chromosomes coincide 
with those expressed by Weismann in one respect, 
that is, they are assumed ‘‘to have definite structures 
and not to be simply bags filled with a homogeneous 
fluid.” Wilson (1912, p. 63) also regards the chro- 
mosomes as “compound bodies, consisting of differ- 
ent constituents which undergo different modes of 
segregation in different species.” 
Students of genetics now consider the individual 
as built up of a number of unit characters represented 
in the germ-plasm by factors, and when two different 
germ-plasms unite (amphimixis) the factors do not 
mix, but remain uncontaminated. The germ-plasm 
of offspring which develop from fertilized eggs is 
supposed to consist of an assortment of factors 
brought about during synapsis and reduction as indi- 
cated in Fig. 84. The factors (or genes) in the germ- 
plasm occur in pairs called allelomorphs,' and one of 
the pair may be regarded as dominant, the other re- 
cessive, as, for example, the yellow and green colors of 
pea seeds. Thus the appearance of the individual 
depends upon the character of its dominant factors. 
Any attempt to account for the origin of new species 
1 According to some investigators, especially in England, the presence 
of a factor should be considered one allelomorph and its absence as the 
contrasting factor. 
