334 KOFOID AND SWEZY. 



that we may have here a case of sex chromosomes among the Protozoa. 

 The instances in which we have determined the number of chi'omo- 

 somes are few and though we have not succeeded in finding a critical 

 case of four chromosomes it may be that some of Kuczynski's determi- 

 nations of four are correct and that both numbers, four and five, 

 occur in the species and possibly in the genus. If this be true the 

 process of gametogenesis and syngamy, in these trichomonads if it 

 occurs, acquires added interest. 



Multiple fission in Trichomonas aiigusfa. 



We have found multiple fission to be a normal phase of wide- 

 spread occurrence in the life-history of Trichomonas augusta and 

 other trichomonads upon which we have worked. It occurs nor- 

 mally and not infrequently in individual hosts. Some hosts contain 

 no evidence of its occurrence, others have large numbers of parasites 

 in some phase of the process. It has been found in Trichomonas 

 augusta parasitic in Rana hoyle'i, Bufo halophilus, and Diemycti/lus 

 torosus, and always in the usual intestinal smears. Binary fission 

 which is not with certainty distinguishable from the first mitosis in 

 multiple fission also occurs in the same preparations with the late 

 stages of the latter process. 



Multiple mitosis results in the formation successively of 2-4-8 

 nuclei by mitosis with the accompanying multiplication of extranuclear 

 organelles, such as cytostoine, motor apparatus including blepharo- 

 plast, undulating membrane (including chromatic marginal filament, 

 chromatin basal rod or parabasal body), paradesmose, and the axo- 

 st^de. The multiplication of the latter by longitudinal division lags 

 behind that of all other organelles so that four nuclei are often seen 

 with two axostyles and eight with four (PI. 4, Figs. 41, 42). 



The result of multiple mitosis is the formation of a syncytium or 

 somatella with eight nuclei each with its full complement of organelles. 

 The nuclei lie in the periphery (Fig. G, 1) with the flagella radiating 

 outwardly and the axostyles pointing subcentrally while the undulat- 

 ing membranes are on surface of the common cytoplasm with their 

 free ends pointed more or less towards the center. Usually one or 

 more, however, have the undulating membrane at the margin of the 

 mass. 



After multiple mitosis is completed plasmotomy ensues. This 

 is not coincident for all merozoites but each detaches itself singly from 



