56 
H. E. Jordan 
the plane of future fission, possibly dividing pairs (except accessory) of 
univalent cliromosoraes equationally, which chromosomes subsequently 
disjoin to form the original groups of 9 and 8 chromosomes respectively. 
It seems vis er to await the probable discovery of a more favorable material 
for the elucidation of this phenomenon than to attempt to use superficial 
facts as arguments for or against the various theories respecting the 
significance of the chromosomes. As regards the question of the genetic 
continuity, or even the permanence, of the chromosomes (individuality 
theory — Boveri) the facts here argue more strongly for, than against, 
the hypothesis (since 9 and 8 reappear idtimately). 
Tlie identity in number and behavior (practically) between the 
chromosomes of opossum and tliose of the domestic guinea (Guyer, 1909b 
— probably also tliose of coc-k — Guyer, 1909a) is very striking. 
In the case of Blatta, Wassilieff (1907) and in that of Gryllus, 
Buchi!ier (1909) believe that the accessory chromosome contributes to 
the formation of the mitocliondria. Goldschmidt (1907) assigns a nutri- 
tive significance to the accessory chromosome. 
b) Synizesis and synapsis (telosynapsis). 
Summary. Delicate chromatic loops are polarized on the idiozome 
in synizesis. Subsequently these loops open up and conjugate in pairs 
at their free ends. A second set of polarized loops is thus formed. The 
latter are considerably eoarser and only about half as numerous as the 
synizesis loops. Düring this process, then, the first numerical reduction 
of the diploid group of chromosomes occurs, and apparently by telosynapsis. 
The fact tliat both in synizesis and synapsis the loops are moniliform is 
further proof of an end-to-end conjugation. The character of the prophase 
clu’omosomes indicates that subsequently the limbs of the loops come 
into dose apposition and simulate a condition of parasynapsis. Indeed. 
the evidence here points to a side-by-side union following a primary 
end-to-end union. If the essence of the synapsis is intermingling of the 
fundamental elements of the chromosomes, then this double method of 
conjugation would seem more effective in producing this result than 
either telo- or para-synapsis alone. 
Literature. The literature of the subject of synizesis and synapsis 
is so c-losely bound up witli that of gametogenesis and chromosome studies 
in general, that it seems impracticable here to attempt to extract the 
one from the otlier. It may suffice simply to note that by far the greater 
number of investigators in this field take the position that synizesis is a 
normal process. A minority contend that it is a fixation artefact. As 
