210 RESEARCH IN PROTOZOOLOGY 



commensal in their mode of life and their morphological characters 

 are so well defined that I do not consider they afiford any problem 

 in diagnosis to the competent worker. 



The questions that may arise over the pathogenicity of Council- 

 mania lafleuri, Karyama'hina falcata, Entainceba paradysenteria, 

 E. macrohyalina, Caudaina'ba sinensis and Craigia may con- 

 veniently be deferred until settlement of their systematic position. 

 Their identity as valid species rests under doubt. 



THE COCCIDIA, PLASMODIUM, LEISHMANIA AND THE INTESTINAL 

 SPIROCHETES AND FUNGI 



Although we have little if any direct evidence concerning coc- 

 cidial infections in man, our general knowledge of the coccidia 

 assumes that the epithelial cells of the small intestine are invaded 

 by Isospora Jioniinis. The only problem that concerns diagnosis 

 lies in the determination as to whether a condition in any way 

 resembling dysentery develops during the course of an infection 

 with Isospora, or whether the abnormal bowel discharges that have 

 been noted by several observers are attributable to other causes. 

 It is conceivable that a massive infection might strip the mucosa 

 bare of epithelium and thus open the way for an acute bacterial 

 invasion. However, I know of no instance of this in man. 



Several instances of infection with Isospora have now been 

 studied. At least four observers, Noc (1920), Haughwout (1921), 

 Connal (1922) and Schule (1927), have noted a periodic diarrhea 

 recurring at rather regular intervals which may be associated with 

 periods of schizogony in the epithelial cells. The occurrence of 

 epithelial cells in the stools of persons infected with Isospora 

 also has been reported, and in one or two instances coccidia were 

 said to have been seen in some of the cells. However, it is as yet 

 unproved that either the periodic diarrhea or the desquamation 

 of the cells were caused by the coccidia. In fact, Connal, in the 

 account of his case, raised grave doubts as to the origin of cells 

 in that manner. Moreover, it is questionable if intracellular coc- 

 cidia would be recognizable after their long journey from the site 

 of infection in the small intestine to the anus. 



Most of the earlier and some of the more recent writers on 

 tropical medicine recognize dysenteries of malarial and leishmanial 

 nature. I never have had the opportunity to study a suspected case 

 of leishmanial dysentery, but I have been able to investigate a few 



