R Kudo 227 
ohlmacheri to a varying degree, lias failed to reveal any evidence which 
might prove the occurrence of an intracellular stage. 
THE TROPHOZOITE. 
The nucleus in the young uninucleate form undergoes division. Its karyo- 
some becomes larger and less dense (Fig. 21). It divides into two equal parts. 
The daughter karyosomes move toward the opposite ends of the nucleus. 
Frequently a deeply staining chromatic strand exists between them for some 
time (Fig. 23). At first, the reticulated achromatic network does not show 
much change, but later it becomes more densely accumulated at the equatorial 
plane together with the chromatin granules (Fig. 23). The nucleus finally 
divides into two along this plane and the two daughter nuclei may remain 
attached to each other (Fig. 24). At the end of the division, the two nuclei 
seem to be similar in structure. Changes in appearance, however, take place 
soon afterward. One nucleus (a) shows a large karyosome which is usually 
attached to the nuclear membrane and a very fine achromatic network, thus 
resembling in appearance that of the uninucleate form before division. The other 
nucleus (6), however, shows a decrease in the size of the karyosome compared 
with the former and chromatin granules become scattered over the coarse 
achromatic network (Fig. 25). The former (a), as its later history indicates, is 
the vegetative nucleus, the latter ( b ) is generative. The two nuclei show a 
striking difference especially when stained with Giemsa’s solution: the vegeta¬ 
tive nucleus assumes a light pink colour with a light bluish karyosome, while the 
chromatin granules scattered on the achromatic network and the karyosome 
of the generative nucleus stain a deep red. 
The generative nucleus undergoes further division without any resting 
period. The division takes place in a similar manner as was stated above for 
the first division, preceded by the division of the karyosome and chromatic 
network (Figs. 26-28). Fig. 29 shows two views of a trophozoite in which 
the two daughter generative nuclei have just completed the division. In well- 
made smears, the distance between these two nuclei is much smaller than that 
between the vegetative nucleus and either one of them. Figs. 30, 31 and 41-43 
show typical trinucleate trophozoites. 
In all known cases, the earliest phase of the trophic life is the uninucleate 
form. Concerning the formation of the binucleate form, there are two views. 
According to Auerbach (1910) in the development of M. bergense, two uni¬ 
nucleate forms come in contact and one of the copulants casts off a part of 
the nuclear substance, thus forming a binucleate form with nuclei dissimilar 
in size. On the other hand, Davis (1916), Georgevitch (1917a), Erdmann (1917) 
and others, maintain that the nucleus of the uninucleate form produces those 
of the binucleate form by division. Of these latter authors, Georgevitch 
thinks that the division is unequal and forms a smaller generative and a larger 
vegetative nucleus. Davis, however, observed equal division so that the 
daughter nuclei were of "equal size and similar appearance.” In Leptotheca 
