230 THE AMERICAN MONTHLY [Aug. 



vital (metabolism) powers in its assimilation and elabora- 

 tion of the various organic and inorganic elements 

 requisite to the successful issue of its full life cycle. 



To describe the character of material used in these de- 

 terminations, I hope I may be excused for being some- 

 what prolix. 



After having studied a special living material during 

 a period of fifteen days — for a few hours each night, the 

 material had become so filled with minute rotifers, that 

 it necessitated securing a new supply of living diatoms. 

 On the 4th of July, being urged on by the desire to solve 

 the phenomenon noted by Prof. H. L. Smith and par- 

 tially verified by myself, I visited an artificial fresh water 

 lake at the Spring Hill College grounds, distant six 

 miles from Mobile, from which locality I had secured the 

 material at first studied. On arrival at the lake I found 

 the lake used for bathing purposes and through the 

 kindly aid of one of the bathers, I secured from the bot- 

 tom of the lake a considerable tuft of eel-grass. I knew 

 that the flat leaves were usually covered with living dia- 

 toms, and that they would be relatively free from sand 

 and mud. This specimen was secured for the experi- 

 mental supply of living diatoms, and while making tests 

 outside of the lake, I found swamp-like spots filled with 

 a reddish or iron-rust colored flocculent deposit. Making 

 a trial test of this material for the presence of diatoms, 

 I noted that it contained dead frustules in abundance. 

 On account of their large and conspicuous sizes I collected 

 a large mass of the vegetable growth and expressed the 

 fluid therefrom into a bottle. It was wide mouthed, 

 cylindrical in shape, an inch and a half in diameter and 

 about four inches deep. I merely saved this material to 

 see what species were present therein, as I did not ex- 

 pect to find living diatoms in the material. On return- 

 ing to Mobile I submitted this material to microscopical 

 examination, when I found that magnificent specimens of 



