230 
A Myxosporidian 
without greatly impeding the function of the host organ. Thus the process 
of gemmation may be interpreted as an adaptation of the parasite to its 
habitat. 
The cytoplasm of the young trophozoite is poorly differentiated. Up to 
the trinucleate stage, the ectoplasm is hardly distinguishable from the finely 
reticulated endoplasm. When fixed, the differentiation becomes less visible 
than in the fresh state. Although there is no difficulty in distinguishing young 
trophozoites from leucocytes in stained preparations (Figs. 109-111), it is 
frequently a hard task to separate them in hanging drop preparations, as 
both form pseudopodia of similar shape, and the nucleus is usually invisible 
(Figs. 105-108). 
THE SPORE FORMATION 1 . 
The trinucleate trophozoite, as was stated before, contains the vegetative 
nucleus and two generative nuclei, each of which becomes a spore by future 
development (Figs. 41-43). Rarely the vegetative nucleus is seen dividing 
at later stages (Fig. 48). This division produces two daughter nuclei, one of 
which remains as the vegetative nucleus of the trophozoite, while the other 
produces a gemma (Figs. 39, 48, 52). A single vegetative nucleus is always 
observable in the trophozoites at later stages of development (Figs. 49-60, 
71, 81-86). 
The division of the generative nuclei is similar to that described before in 
the case of the primitive generative nucleus. It is preceded by the elongation 
of the nucleus in the shape of a spindle and the division of the karyosome. 
The chromatin granules scattered on the network become separated into two 
groups, each condensing near the end of the spindle (Fig. 44). After the com¬ 
plete separation of the karyosomes, the separated chromatin granules surround 
each of the former (Figs. 45, 48, 49) and the daughter nuclei finally result. 
Since the divisions of the two generative nuclei may or may not take place 
simultaneously, there are seen trophozoites, the number of whose nuclei vary 
from five to thirteen (Figs. 45-54). I shall describe the divisions of one of the 
generative nuclei, as those of the other are essentially the same. 
The generative nucleus (Figs. 41-43) divides once and forms two daughter 
nuclei, one for the spore membrane and the other for the sporoplasms and the 
polar capsules (Figs. 45-47). The former divides again forming two nuclei, 
1 Young as well as sporulating trophozoites were abundantly present in the tubules of the 
kidneys of every infected host animal. At the time when Ohlmacher and Whinery studied the 
Myxosporidian, very little was known regarding the Myxosporidia possessing in their life cycle 
small trophozoites and living in the organ cavities of the host. On the other hand, Myxosporidia 
that produced large cysts in the host tissue or that developed into large vegetative forms 
such as Sphaeromyxa ( Cystodiscus) immersa, were comparatively well known. It seems probable 
that these authors searched for large cysts or trophozoites, and overlooked the relatively small 
vegetative forms as stated here. In this connection, Ohlmacher states that “it is probable that, 
in this case, the parasite did not reach its adult condition in its batrachian host; but here only 
passed one stage of its evolution; that is, the spore stage.” The inaccuracy of this statement is 
obvious. 
