lODAMOEBA BUTSCHLII II9 



or water lor two or three weeks ; but they are unable to withstand 

 drying, like those of the other intestinal amoebae. Their development 

 in a new host has still to be determined. Doubtless they hatch in the 

 small intestine, and each liberates a single uninucleate amoeba. 



Descriptions and figures of the cysts of /. biiischlii have already been 

 given by Wenyon (1915^), Wenyon and O'Connor (1917), Kuenen and 

 Swellengrebel (1917), Brug (1917, 1919), and Flu (1918). All have noted 

 their striking appearance in iodine solution, but only Kuenen and 

 Swellengrebel have stated that the " iodophilic body" is composed of 

 glycogen. Wenyon and O'Connor note that they vary greatly in size and 

 shape, and give their size as yyu, to 15 /a " or more." They do not mention 

 the volutin granules in the cysts; but Kuenen and Swellengrebel observed 

 them, and apparently considered them to represent the "peripheral 

 chromatin" of the nucleus extruded into the cytoplasm. Brug (1917) also 

 noted these granules, but was unable to interpret them. He calls them 

 " coccoid corpuscles," and says they may be parasites, " saprophytes " 

 (s/c), or metabolic products. He describes the "peripheral chromatin " 

 of the nucleus as being disposed in the form of a crescent — an appear- 

 ance resulting, apparently, from defective fixation. The size of the 

 cysts is given by Kuenen and Swellengrebel (1917) as 10 fx to 12 //, — 

 the same size as their amoebae. Flu (19 18) describes the cysts as 

 " spherical bodies with a large vacuole, which . . . assumes a more 

 or less brown colour" in iodine solution. His fi-gures are very poor, 

 and he considers the " bodies " — as already noted — to be degenerate 

 cysts of E. histolytica. 



I believe that there are different races of /. hi'itschlii which are 

 distinguishable by the sizes of their cysts — as in E. liistolytica and E. coli. 

 Certainly a distinct difference is sometimes observable in the size of 

 the cysts passed by different persons. But the cysts are so difficult to 

 measure that 1 cannot place much confidence in such measurements 

 as I have made, and I am therefore unable to offer any proof of the 

 existence of such races at present. 



Occurrence. — There can be no doubt that /. biitschlii has a wide 

 geographical distribution. It occurs in Egypt (Wenyon and O'Connor), 

 the South Seas (Prowazek), the Dutch East Indies (Kuenen and Swellen- 

 grebel, Brug, Flu), and I have found the cysts in the stools of patients 

 who have been invalided to England from all the chief areas of the 

 present war. The infected cases examined have included persons from 

 all the five continents ; but it is, of course, impossible to discover where 

 or when their infections were acquired. The organism occurs also in 

 persons who have never left the British Isles.* 



Wenyon (1916) found the cysts of /. biitschlii in the stools of 29 out 

 of 51^6 cases of dysentery and other intestinal ailments invalided to 

 England from Gallipoli in 1915. They have since been found in a 

 similar proportion of cases of dysentery, etc., from all the theatres of 

 war, by many other workers in England. My own records show that 

 they must occur in at least 5 per cent, of all the cases examined, 

 but the exact incidence I cannot determine : for different series of 

 patients have been examined with different degrees of thoroughness, and 

 I have examined many stools selected because they contained the cysts, 



• Cf. Matthews and Malins Smith (1919). 



