THE AMERICAN 



MONTHLY 



Studies in the Biology of the Diatoms. 



Bv K. M. CUNNINGHAM, 

 MOBILE, ALA. 



Within the past year, various matters appertaining to 

 the DiatomacejB, drew my attention strongly to the ques- 

 tion of their plant or animal nature ; and in order to de- 

 termine, or substantiate by personal observation, and 

 experiences, I adopted as my initial task, the verifica- 

 tion of the presence or absence of an investing protoplas- 

 mic covering or sheath ; somewhat after the method 

 suggested by Cornelius Onderdonk, as given in his arti- 

 cle in *' The Microscope'' for August, 1890 ; but, after the 

 inception of my experiments, I very soon ascertained 

 that his method, while novel and interesting, -per se, is 

 not at all essential for the purpose in view, as I found a 

 more direct and satisfactory method, and one which does 

 not require the use of staining agents, or the effects of 

 staining agents to determine the question. 



After having made a number of satisfactory observa- 

 tions on the motion and other aspects of the living dia- 

 toms from special brackish and fresh water gatherings ; 

 I condensed my experiences in a paper which was read 

 before the New York Microscopical Society and after- 

 wards published in the Journal of the society in its Oct., 

 1893, issue ; wherein I outlined my reasons for presum- 

 ing that the Diatomacese properly belonged to the char- 

 acter of animal life classed under the Protoza, rather 

 than to the Vegetable Kingdom or plant life. 



The appearance of my paper on the subject resulted in 



