No. 498] 



NOTES AND LITERATURE 



427 



he has allowed his imagination to lead liim into generalizations 

 involving totally different organisms. Here is one danger of the 

 use of artificial culture methods in studying protozoa. The enor- 

 mous numbers obtained tend to obscure the varying phases of 

 vitality that characterize the life cycle of protozoa. The study 

 of protozoa, even when it is possible to apply bacteriological 

 methods, is fundamentally different from bacteria study. The 

 latter dependent upon growth conditions, colony formation, re- 

 actions to media, etc., are essentially physiological. Protozoa 

 study, on the other hand, is essentially morphological and is 

 based upon the structures of the protozoan cell, involving all 

 changes in cell structure which an individual (in the cyclical 

 sense) undergoes during various phases of vitality. Hence it 

 becomes necessary, first of all, to know the life history of a 

 protozoon and the fundamental structures which its protoplasm 

 assumes at different periods of vitality. Mere number of cells 

 in any given phase is not satisfactory and here is where Walker 

 falls into a trap. He fails to find stages described by Schaudinn 

 and Wenyon, in his agar cultures and gives the inference at 

 least that their observations were incorrect, all without taking 

 the trouble to obtain his organisms in the corresponding stages 

 of vitality. Schaudinn, in one set of observations to fill out the 

 sexual phase of the life history, watched his material for weeks 

 without finding the stages desired, and. to get them, finally 

 swallowed the contents of a number of dishes, thus inocu- 

 lating himself. His experiment was successful and he ob- 

 tained what he wanted. This heroic method of procedure is 

 not absolutely necessary, for abundant material may be obtained 

 by inoculating lower animals; even such experiments, however, 

 were not made apparently or, if made, not described by Walker. 

 Such neglect vitiates all criticism or comment by the author, 



of conclusions of others regarding the sexual cycle of intestinal 

 rhizopods and a fortiori of free-living Amaha proteus, an en- 

 tirely different kind of organism. 



Not even in regard to the ordinary vegetative phases of his 

 organisms does Walker do justice to the material. The un- 

 doubted reproduction by budding is entirely overlooked; the 

 term "spore" is misused throughout and the "extrusion" of 

 fully formed reproductive bodies is very questionable. If such 



