THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. XVIII. FEBRUARY. 1897. No. 2 



Studies in Diatom Biology. 



By K. M. CUNNINGHAM, 

 MOBitE, Ala. 



During the month of November, 1895, I had an oppor- 

 tunity of securing a very interesting gathering of living 

 diatoms under the following conditions. On one of my 

 excursions I incidentally noted that the surface of a ditch 

 used for transporting saw logs through a marshy flat, was 

 covered with a thick and uniform layer of greenish scum, 

 and that it was accidentally banked up at the point, by a 

 boat paddle arresting its passage along the ditch. The 

 winds were driving further sup{)lies of scum to the ob- 

 struction across the ditch. A momentary inspection in- 

 dicated that there was a very rich accumulation of dia- 

 toms. I secured a pint or so of the material for treat- 

 ment and study. The chief or most numerous form oc- 

 curing in tlie gathering was Nitzschia scalaris, which 

 si)ecies, as is well known, is among the largest of the 

 prism-like forms commonly encountered all over the 

 globe, and is associated with fresh or brackish waters. 

 By availing myself of the aid of this special form in its 

 living state, 1 was enabled to prosecute some studies tend- 

 ing to ii^ive additional importance to the hypothesis that 

 this diatom belongs biologically to the protozoa rather 

 than to tlie plants, [shall indicate by what line of reas- 

 oning I venture to present this view to the attention of 

 those who are interested in biological studies. 



As a primary fact, we may assert that when a portion 



