40 THE AMERICAN MONTHLY [Feb. 



diatom had tractive power suflBcient to push or pull a 

 mass of obstructing matter equal to its own bulk or even 

 greater. In connection with these remarks, it may be 

 proper to relate that he has recently been cultivating or 

 growing the living forms and kindly offered to mail to 

 me a culture sample. But we feared that they would 

 not arrive in good condition if sent. 



Acting on a suggestion derived from H. L. Smith's 

 work in relation to the action of alkali on the protoplasm 

 of the living frustules in an experimental way, I found 

 that if a mounted slide of living diatoms was immersed 

 in strong white soap solution and set aside for about 

 twenty-four hours, all the frustules containing the living 

 endoplasm were burst asunder into numerous small frag- 

 ments, and the greenish contents were driven out and 

 distributed in rills over the slide. This also showed that 

 sutural lines are weak points in the frustural box. 



In an attempt to clean a considerable quantity of ma- 

 terial, from which the studies of Nitzschia scalaris were 

 made, by boiling in a pearline solution, the result showed 

 that the recent species had become badly distorted by a 

 partial solvent action, and a softening of the silex. This 

 I had never previously noticed in acid treatment, but I 

 had been aware of the necessity of using the alkalies cau- 

 tiously in one stage of the cleaning process. 



Those who undertake to solve for themselves the mys- 

 terious cause of motion in the diatoms, will be confronted 

 with a species of phenomena of the most puzzling inter- 

 est. If the living diatoms have been retained in the 

 same bottle of water for a period extending over three 

 days or more, the study will be complicated by the growth 

 in the water of several kinds of spirillum, which are apt 

 to colonize around the edges of all diatoms. When this 

 is the case, ii may so happen that when a large Navicula 

 is being closly studied in the field in expecting to detect 

 some characteristic of motion, the mind will suddenly be 



