136 D. H. WENRICH 



chomonads named (T. muris, T. augusta, T. Caviae, and T. 

 batrachorum) contain seven sharply outlined chromosomes 

 although in many cases, of which a number have been pictured 

 (e.g., plate I, figs, 16, 17; plate II, fig. 20; plate IV, fig. 57; 

 plate VII, fig. 96), the probability is great that the position of 

 the chromosomes interferes with the certain recognition of an 

 eighth. Chromosome-groups of only six, of uncertain separa- 

 tion, occur much more seldom." In all the figures mentioned 

 in the quotation (except in fig. 96), and in some others not 

 mentioned, the groups can be resolved into six split prophase 

 chromosomes and one caryosome. In the few cases where 

 Kuczynski thinks he finds eight, I am inclined to the belief 

 that he may have counted as separate chromosomes the two 

 parts of one which had become rather widely separated; then, 

 with the caryosome, the number eight is obtained. 



Kofoid and Swezy ('15) give five as the chromosome number 

 both for the prophases and the metaphase for T. muris and T. 

 augusta. If the form which they called T. muris is the same 

 species as the one I have been studying, the difference in chromo- 

 some number needs to be accounted for. I will merely refer 

 to the great difficulty in elucidating these small details in such 

 minute organisms, even when the technique has been good, and 

 to the further possibility that the form studied by them was of a 

 different species. 



As for other species, since Kuczynski finds and figures con- 

 ditions in T. caviae so similar to those in T. muris, I am inclined 

 to believe that there are six chromosomes in T. caviae. Dobell 

 ('09) found six chromatin bodies in T. batrachorum, but hesitated 

 to call them chromosomes. Martin and Robertson ('11), on 

 the other hand, described for T. eberthi eight prophase and four 

 metaphase chromatin units, although they prefer not to call 

 them chromosomes. It can hardly be argued that all species 

 of Trichomonas should have the same number of chromosomes, 

 but since Dobell and Wenyon have both found six and since the 

 numbers in the species studied by Kuczynski are probably six 

 instead of eight, the situation in T. eberthi^ might bear rein- 

 vestigation. 



