754 THOS. H. MONTGOMERY, JR. 
parasyndesis in Plethodon such as Janssens had described for 
this object and the Schreiners for Salamandra. 
The main difference between the views of parasyndesis and 
metasyndesis lies in the interpretation of the longitudinal cleft 
of the gemini. 
The question has been much discussed as to Bal what takes 
place during the conjugation (zygotenia) of the chromosomes; 
whether there is actual fusion of them, or substance interchanes 
or simply a close interlacing. The phenomena in Euschistus 
do not indicate any fusion of the conjugants, for it is generally 
possible to distinguish the two components of each geminus even 
in the iam conditions. I have compared (’01) this process - 
with the conjugation of Protozoa, and it may indeed be the same 
as in the conjugation of two Paramaecia, the two individuals 
being for a while so closely apposed that no line of demarcation 
can be seen between them, while afterwards they separate into 
the same two individuals as before. In the Ciliata there is inter- 
change of substance between the conjugants, so that one would 
anticipate a similar process in the case of conjugating chromo- 
somes, but this cannot be determined without instituting careful 
microchemical studies upon the chromosomes before and after 
the pachytene stage. 
A minor point remaining to be mentioned is that in Euschis- 
tus the nucleus of the mature sperm is a cylinder of chromatin 
around a central core of karyolymph, and is not a solid mass of 
chromatin. <A similar condition was noted by Baumgartner 
in Gryllus (02). For the most part describers of insect sperm- 
atogenesis have delineated the chromatin of the nucleus as dis- 
integrating into fine granules which later condense into a solid 
mass. This matter is worthy of some consideration by those 
interested in microchemical studies of sperm heads; for these are 
by no means pure chromatin, as sometimes supposed, but con- 
tain some cytoplasm, the substance of the perforatorium, and a 
considerable amount of karyolymph. 
