PATHOGENIC PROTOZOA. 411 



Walker* has published a full account of his work on the 

 cultivation of parasitic amebae. 



While giving due credit to the large amount of valuable 

 work done by others in the study of amebae, Walker has 

 perfected the methods of study to such an extent as to make 

 this branch of investigation now within the range of exact 

 observation. Walker's original article is recommended to 

 those who wish to persue the subject fully; but the following 

 description taken from his paper may serve as a guide, and 

 may perhaps enable the student to begin investigations into 

 this subject which is increasing in importance daily. 



Cultivation of Amebce. The medium best suited for the 

 growth of amebae is that introduced by Musgrave and Cleggt 

 which consists of: 



Agar 20.00 



Sodium cHorid 0.3-0.5 



Extract of beef 0.3-0.5 



Distilled water 1,000 



This medium is prepared as ordinary culture-media for the 

 cultivation of bacteria, except that the reaction should be i 

 per cent, alkaline instead of the 1.5 usually employed for 

 bacteria. Ameba cultivated upon this medium will after- 

 wards grow less readily than at first upon liquid media, but 

 they grow more readily upon the solid medium than in liquid 

 media when transplanted from the latter to the former. 

 Ameba fecalis is the only one which grows on an acid medium. 

 All ameba require the presence of bacteria in the culture- 

 medium and it seems that the bacteria are either eaten by the 

 ameba or that they transform the medium in some way so as 

 to make it assimilable by the amebae. Moisture is even more 

 essential for the growth of amebae than for that of the bacteria. 



*Journ. Med. Research. Vol. XVII., No. 4- (New Series, Vol. XII. Feb., 

 1908. pp. 379-457.) 



fDept. of the Interior. Bureau of Gov., Labs., Biolog. Lab., No. 18. Oct., 

 1904. Manila Bu. Pub. Printing. 



