10 University of California Publications in Zoology ["^'ol. 16 



found in a single central or in several irregular grannies (pi. 1, figs. 

 11-16). The nuclear membrane is always present and the nuclear 

 network within can usually be demonstrated. The kinetonucleus 

 stands out very prominently as compared with that of the non- 

 flagellated forms. 



In connection with the preflagellate stage some interesting forms 

 have been found (pi. 1, figs. 14-24) wherein there is an elongate 

 flagellate bearing a small, round, non-flagellated form near the end of 

 the flagellum. No explanation of these forms can be made as yet, but 

 it is strongly suggestive of sexual reproduction. Careful observation 

 of the living material does not indicate that we have here a process 

 of unequal longitudinal division. A parallel case has been observed 

 in the living material of Herpetomonas muscae domesticae. Patton 

 (1908) also shows elongate flagellates with several smaller oval forms 

 in a similar position (pi. 1, figs. 9-10) with the explanation that the 

 figures are a result of the way in which multiplication has taken place. 



In addition to the method of movement described for the elongate 

 flagellates, a flagellate such as is seen in plate 1, fig. 13, progresses 

 with a serpentine movement with the posterior end directed forwards. 

 Such a flagellate has been observed to bore its way into cellular masses 

 in the li\ing material, the posterior end entering first. 



Following the appearance of the preflagellate forms just described, 

 there are great masses of Leishmania-like forms found in the lumen 

 of the stomach. The evidence points to the fact that the flagellates 

 described above undergo a multiple fission process, either intracellular 

 or extracellular. Direct evidence of the intracellular forms has not 

 yet been found in sections of the epithelial lining of the stomach, 

 but the so-called tailed and tailless spheres (Minchin and Thomson, 

 1915) have been found in cellular masses on smear preparations. As 

 seen on plate 1, figure 26, there is a flagellate rounding up to form a 

 tailed sphere. The tailed spheres have been studied in the living 

 material also. The movement is slow. The flagellum of the parent 

 lashes about feebly while within there are found a variable number of 

 almost mature flagellates wriggling about. Whether the organisms in 

 plate 2, figures 29-32, can be interpreted as tailless spheres is some- 

 what doubtful, but this is the most plausible explanation. Upon de- 

 velopment they seem to give rise to a large plasmodial mass in which 

 are the small merozoites (pi. 2, fig. 37). Frequently a large number 

 of the small multiple fission forms, or merozoites, are found free from 

 the Plasmodium (pi. 2, figs. 38-45). On the one hand, development 



