TEICHOMONAS MURIS 663 



Lwoff (1925), referring to the form in E. coli and E. histolytica, suggests 

 that it is distinct from the one which parasitizes free-living amoebse, and 

 proposes to name it S. normeti. The development of the organism is a 

 simple one. A spore enters the cytoplasm and grows into a multinucleated 

 sphere enclosed by a membrane. It breaks up into a number of spores, 

 which are not provided with flagella (Figs. Ill, 4, and 173, 4). The spores 

 escape from the cyst, and after entering the cytoplasm of other amoebse or 

 flagellates, repeat the process of growth and spore formation. 



T. muris multiplies by longitudinal fission (Fig. 271). The first step 

 in the process is the division of the two groups of blepharoplasts, so that 

 two pairs are formed. These separate from one another, and as they do 

 so they are seen to be connected by a fibre, the paradesmose, which may 

 still persist even when the blepharoplasts have reached opposite sides of 

 the body. From the anterior of the two new blepharoplasts three flagella 

 arise, while from the posterior one a new basal fibre grows out parallel 

 to the pre-existing one. At the same time a new membrane forms as a 

 new axoneme grows out from the anterior blepharoplast. The new 

 membrane, axoneme, and basal fibre gradually increase in size till they 

 equal those already existing. Meanwhile, the nucleus has been under- 

 going changes. The fine chromatin granules run together to form definite 

 chromosomes. The writer (1907) concluded there were six of these, but 

 Kofoid and Swezy (1915a) give the number as five and Kuczynski (1918) as 

 eight. Wenrich (1921) has published a clear account of the division stages of 

 T. muris, and has shown that there are actually six chromosomes (Fig. 271). 

 The nucleus becomes elongated, the nuclear membrane persisting during 

 the whole process of nuclear division. Each chromosome then becomes 

 constricted and divided into two, so that six pairs of chromosomes can 

 be seen. The nucleus becomes elongated, and one set of daughter chromo- 

 somes passes to one end of the nucleus and the other set to the other end. 



The nuclear membrane becomes constricted and divided. The chromo- 

 somes in each daughter nucleus now break up into finer granules, and 

 the original type of nucleus is reproduced. During the nuclear division 

 changes have been occurring in the axostyle. Here, again, there is a 

 difference of opinion as to what actually happens. The writer (1907) 

 believed that, as the blepharoplasts separate, the axostyle was divided 

 longitudinally from before backwards. Eventually, the two daughter 

 axostyles were united only at their posterior extremities. By this time 

 the flagella, membrane, and other parts of the new flagellate were fully 

 formed. The cytoplasm became elongated, and had nucleus, blepharo- 

 plasts, cytostome, and flagella at each end, while stretching between the 

 blepharoplasts were the axostyles, united by their tips at the middle of the 

 elongated body. The cytoplasm was then divided between the axostyles, 



