A Coniparative Study of the Chromosomes etc. 
275 
early growth period of the germ cells there is an intmiate approximation 
of the chromosomes (parasyndetically or metasyndetically) into pairs, 
each of which is composed of two homologous chromosomes, one maternal, 
the other paternal (Moxtgomery) ; 7. that during the growth period there 
is either a) a transfusion of substance between the members of a double 
thread, or b) the two chromosomes fuse together into a single thread, 
which later may fall to separate along the line of fusion, or c) whole Seg- 
ments (internodes of the strepsistene stage) of the twisted threads are 
transposed from one chromosome to the other, or d) the chromosomes 
remain unaltered in themselves and synmixis is brought about by the 
maturation divisions (rotation, permutation, etc.); 8. that the matura- 
tion divisions bring about the Separation of chromosomes which are 
qualitatively unlike, and thus reduce the number of chromosomes (and 
the determiners) to one half that of the soma cells. 
Thus we have two complementary sets of phenoniena, one mani- 
fested in the inheritance of organisms, the other manifested in the pro- 
duction of their germ cells; there can be no doubt that the rediscovery 
of Mendel’ s law has done much to increase the study of maturation 
of the germ ceUs and to throw light upon the significance of the pro- 
cesses seen there. It is to Montgomery (’Ol) first of all that we owe 
theideaofthe pairing of the diploid complex of chromosomes bymeans 
of size relations into two groups, one set maternal, the other set paternal, 
and the formation of the gemini of the first maturation division by the 
Union of homologous pairs of chromosomes of the two groups. Later 
it was maintamed that the cliromosornes could be paired, not only in the 
matter of size, but also because of similarity of form (Baumgartner ’04; 
Blackman ’IO). SuTTON (’03) and Boveri (’04) found in these facts a 
mechanism for the explanation of the phenoniena exhibited in alternative 
inheritance (Mendehan inheritance). Assuming that the chromosomes 
of a germ ceU are qualitatively different, then in the pairing of the chromo- 
somes previous to maturation allelomorphic pairs of determiners are 
brought together by the conjugation of homologous chromosomes (one 
maternal, the other paternal) ; then, by the Separation of the components 
of the gemini (reduction division) and the inclusion of one set of chromo- 
somes, partly maternal and partly paternal (following the law of pro- 
babüity), in each of the two resulting ceUs, the members of the aUelomor- 
phic pah's would be segregated as required to explain Mendelian inheri- 
tance. This would be in perfect agreement with Mendel’ s law, were a 
single chromosome the bearer of only one unit character, an assumption 
which is not, however, borne out by the facts of breeding, for there seem 
