STRUOTURE AND LIFE-HISTORY OF COPROMONAS SUBTILIS. 111 
conjugants exist in a few forms—in trypanosomes and their 
allies, and in Bodo lacertex. 
Conjugation has not been proved to occur in the Chromo- 
monadina, and no proof of its occurrence in the Huglenoidina 
has been given before. Indeed, Copromonas is the only 
uniflagellate monad—with the doubtful exception of the 
“uniflagellate monad” of Dallinger and Drysdale, the 
“Monas dallingeri” of Kent—which has had its life- 
history worked out. And even in this I cannot claim that it 
has been done with completeness. There can be little doubt 
that there is still much more to be discovered of the ways of 
life of Euglena and its allies. The observations of Kntz, 
Zacharias, or others have certainly not proved that conjuga- 
tion takes place in this order. 
Nuclear Reduction. 
A reduction of the nuclear chromatin is a phenomenon 
which is usually met with in connection with conjugation. 
Leaving the Phytomonadina out of the question for the 
moment, it may be stated that nuclear reduction occurs in all 
flagellates as a preliminary to karyogamy. It has been 
observed in every case where accurate investigation has been 
made. 
The most common method by which this is affected is by 
two divisions of the gamete nucleus, resulting in the forma- 
tion of two reduction nuclei (“ polar bodies,” “ Richtungs- 
kérper”) and areduced gamete nucleus. The reduction nuclei 
degenerate, and the reduced nuclei approach one another and 
fuse. Such phenomena occur in 'l'richomonas intestinalis 
(39, 44), in Bodo lacerte (89), in Hexamitus intestinalis 
(39) and in the autogamy of Trichomastix lacerte (39). 
Reduction divisions of both trophonucleus and kinetonucleus 
are found in trypanosomes and allied forms. And, as I have 
already shown, a nuclear reduction consisting probably in two 
reduction divisions (see p. 97) takes place in Copromonas. 
In Monas vivipara reduction appears to be brought about 
by the expulsion of chromidia from the nucleus (36). 
