344 KOFOID AND SWEZY. 



merozoites occurs by the successive detachment by plasmotomy of 

 single individuals, resulting in plasmodia with 7 (Fig. 73), 6, 5 (Fig. 74), 

 4 (Fig. 75), 3 (Fig. 76), and 2 nuclei. A plasmodesmose indicating 

 recent plasmotomy is seen in some cases (Fig. 77) . The later phases 

 of this process are marked by the aggregation of the nuclear chro- 

 matin in larger karyosomes (Figs. 74, 77, 78) and the disappearance 

 of the dense intranuclear chromidial cloud. In one case, possibly 

 pathological (Fig. 76), the cytoplasm was crowded by many large 

 deeply staining chromidial spheres approaching the nuclei in size. 

 The process of multiple fission in Tetratrichomonas is similar in its main 

 outline and its end result to that in Trichomonas augusta as previously 

 described by us. 



Eutrichomastix serpentis (Dobell). 

 Plates 6, 7, Figures 79-104. 



Material. 



This small flagellate was found in three snakes from California, 

 to wit, in the yellow gopher or Pacific bull snake (Pituophis catenifer 

 (Blainville)), in four of the five individuals examined, in the common 

 garter snake {Eutaenia sirtalis (Linn.)), in one of the two examined, 

 and in the Pacific rattlesnake {Crotalus oregonus (Holbrook)) in the 

 one individual examined. It was also found in one of four individuals 

 of Python reticulatus (Schneider) from Borneo examined at least 

 twenty-four hours after death. 



The parasites were found in each host in greatest abundance in the 

 upper part of the large intestine. Smears prepared from the wall in 

 this region contain division stages of Eutrichomastix in such numbers 

 that it has been possible to work out both binary and multiple fission 

 in this species. 



Historical. 



A flagellate parasite of the intestine of snakes was first described 

 by Hammerschmidt (1844, 1845) from Coluber (= Tropidonotus) 

 natrix as Bodo colubrorum. We have seen only the translation of his 

 paper (1845) but from the crude figures therein reproduced it is quite 

 impossible to determine with certainty what genus he had in hand. 



