322 KOFOID AND SWEZY. 



Except for the spherical form of these individuals with transversely 

 dividing chromosomes, there are no evidences of approaching mori- 

 bundity. But the cells with the other type of division are also rounded 

 up. It is thus possible, but inherently improbable, that these cells 

 represent an unusual type of division of the chromosomes, rather than 

 a stage of temporary telosynaptic fusion subsequent to an earlier 

 longitudinal splitting. 



A precocious longitudinal splitting or perhaps more precisely an 

 emergence of the chromosomes from the chromatic net or spireme in 

 the form of threads apparently split longitudinally has been described 

 for the vegetative cells of certain higher plants by Gregorie (1906) 

 and for Allium and Vicia by Lundegardh (1912). Flemming long ago 

 (1891) noted it in the somatic cells of the salamander and Dehorne 

 (1911) in cells of annelids and trematodes, but it has not been promi- 

 nent in recent cytological investigations of metazoan somatic cells. 

 In none of these cases, however, is precocious splitting followed by a 

 telos\Tiaptic fusion on the equatorial plate such as we have suggested 

 here for Trichomonas, though Gregoire figures a re-fusion of the split 

 chromosomes before the equatorial plate stage. 



The acliromatic spindle is feebly developed. It consists of a few 

 faint fibrils within the intact nuclear membrane which pass from the 

 chromosomes to the centrosomes or blepharoplasts at the poles of 

 the now somewhat elongated, broadly fusiform, or ellipsoidal nucleus. 

 These spindle fibers are more distinct near the centrosomes and as the 

 chromosomes part (PI. 2, Fig. 23) faint interzonal fibers appear 

 between them. There is no satisfying evidence of the formation of 

 astral rays in the cytoplasm at the poles about the blepharoplasts or 

 the centrosomes. A faint starlike structure (PI. 2, Fig. 21) seen in one 

 instance in the cytoplasm about one of the centrosomes is not of 

 general occurrence. 



The paradesmose is formed between the two divided blepharoplasts 

 as they migrate to their polar positions in the spindle. Structurally 

 it is a fiber of uniform caliber lying at all times outside of the nuclear 

 membrane and is directly continuous with the blepharoplasts which it 

 connects. It stains an intense black as do other intracytoplasmic 

 derivatives of the blepharoplasts. 



This organ has been called the axostyle (x\chsenstab) by Prowazek 

 (1904) who discovered it, since he confused it with the development 

 of that structure. Dobell (1909) also fell into the same error of 

 regarding the axostyle as derived from the chromatic fiber joining 

 the daughter blepharoplasts in mitosis, saying "the axostyle is the 



