84 HUMAN INTESTINAL PROTOZOA IN THE NEAR EAST 



the single-nuclear E. histolytica cyst, and, furthermore, it is different 

 in appearance and structure. In one or two cases we have come 

 across fairly large infections of cystic structures which resemble 

 the I-cysts in every way except for the absence of the iodophilio 

 body. These caused us a good deal of difficulty as there was a 

 decided resemblance to E. histolytica cysts. After careful observa- 

 tion of the cases it was possible to make up one's mind that these 

 were really I-cysts minus the iodophilic bodies. In typical I-cyst 

 infections, where the majority of the cysts have the characteristic 

 iodophilic bodies, a few may be seen in which these are absent 

 (Plate III, fig. 15).* 



In one or two cases there have occurred in the stool large 

 spherical cysts which look very much like cysts of E. coli with a 

 single nucleus. In stained films or iodine preparation each is seen 

 to have a single nucleus, which is a spherical body with a very thick 

 nuclear membrane, while the central part is clear and unoccupied 

 by granules or other structures. It has the appearance of a 

 homogeneous body with a central vacuole. When first seen it was 

 thought the cysts were peculiar forms of the cysts of E. coli, but 

 by following the cases for a few days it was found there was no 

 tendency for recognizable stages of E. coli cysts to appear. It was 

 evident that they were not amoebic cysts. It seems most probable 

 that they represent large I-cysts which are devoid of iodophilic 

 bodies or structures of an allied nature. One such case as this was 

 seen by one of us during the routine examination in London of 

 patients returning from Gallipoli at the end of 1915. 



(19) Blastocystis. 



These organisms are of exceedingly common occurrence, at least 

 a quarter of the stools examined containing them. In certain cases 

 they are present in very large numbers and the largest infections 

 we have seen have been associated with an acute diarrhoea. Under 

 these conditions one often notes abundance of very large forms quite 

 as large and even larger than cysts of E. coli. On the other hand, 

 there may be an overwhelming infection of very small forms. 

 Whether large or small, it will be noted that under these conditions 

 the blastocystis are mostly in various stages of division, suggesting 

 that active multiplication is taking place. 



Often the blastocystis occur in large clusters, and on one 

 occasion such a cluster was enclosed in a definite cyst, reminding 

 one of the multiple division stages described by Alexeieff (text fig. 5). 



See inset between pages 148 and 149. 



