266 WALKER. 



in the Bureau of Science for the opportunity and for the assistance in 

 obtaining it. 



The culture medium employed has been for the most part the standard medium 

 of Musgrave and Clegg (1904). Several modifications of this medium have 

 been tried, including the substitution of nutrient bouillon, peptone, dextrose, or 

 peptone and dextrose for the beef extract, and leaving out the salt and nutrient 

 substances altogether. The cultivable amoebse appear to grow equally vrell on 

 any of these media. Tlie methods employed in making these cultures and in 

 isolating pure cultures of the amoebae are those devised by Musgrave and Clegg 

 (1904) and by me (Walker 1908) and are sufficiently well known not to need 

 repetition here. It has not been considered necessary in this morphologic study 

 to isolate the pure cultures of amoebae with pure cultures of bacteria. 



Two hundred and seventy-nine cultures have been made from the stools 

 of 113 cases of amcebiasis without symptoms of dysentery, 158 cultures 

 from the stools in 21 cases of amoebic dysentery, and 27 cultures from 

 the pus of 2 cases of amoebic liver-abscess, in all 464 cultures from 136 

 cases of amcebiasis. These cultures have been made in every case from 

 fresh material in which living amoebfE had been demonstrated micros- 

 copically, usually in the motile condition, sometimes encysted, and often 

 in large numbers. 



Growth of amoebae in the cultures was obtained in 6, or 5.3 per cent, 

 of non-dysenteric cases, and in 2, or 9.2 per cent, of the cases of amoebic 

 dysentery. All of the 27 cultures from the 2 cases of amoebic liver-abscess 

 were negative. Growth of mastigamcebae, flagellates, and ciliates was 

 obtained in the cultures from several of the cases. In addition to these 

 8 cultures of amoeba grown by myself from the intestinal tract of man, 

 one culture isolated by Dr. E. B. Vedder from a non-dysenteric stool 

 at the Division Hospital in Manila, one culture isolated by Dr. Marshall 

 A. Barber from a case of diarrhoea in Kansas, one stock culture in the 

 Biological Laboratory of the Bureau of Science from a case of amoebic 

 dysentery, and one culture isolated by Musgrave and Clegg (1904) from 

 a case of amoebic dysentery in Manila have been available for study. 



A study of these 12 cultures has disclosed 5 well defined species (Plates 

 II and III). Among the 8 cultures from persons showing no symptoms 

 of dysenter}^ there are 4 different species. Among the 4 cultures from 

 cases of amoebic dysentery as many different species are represented. Of 

 the latt^er, amoeba 8 is the same species as amoebse 1 and 20,850 from 

 non-dysenteric stools (Plate II, fig. 4) ; amoeba 14,965 is the same species 

 as amoebas 7, 7,658, and 20,998 from non-dysenteric stools (Plate II, tig. 

 5) ; and amoeba 7,671 is the same species as the amoeba isolated by Barber 

 from a case of diarrhoea in Kansas (Plate II, fig. 6 and Plate III, fig. 7). 

 Amoeba 9 grown from a non-dysenteric stool and amoeba "L" isolated 

 by Musgrave and Clegg (1904) from a dysenteric stool (Plate III, fig. 8) 

 are not duplicated among the cultures. However, amoeba 9 is of the 

 same species as the amoeba cultivated from 22 out of 25 samples of watei- 



