34 THE AMERICAN MONTHLY [Feb. 



of the material is gathered in its densest state, it is intro- 

 duced into a suitable bottle, and tlie diatom contents are 

 allowed to distribute themselves in the water. It is soon 

 evident that many of the motile forms in the bottle are 

 attacliiug themselves to the inside surface of the bottle 

 and continue their motions incessantly in any chance di- 

 rection. If now while having a bottle of this kind under in- 

 spection, as simple an apparatus as a common five cent 

 leas, of a quarter inch focus will enable anyone to follow 

 the motions of the large Nitzschia scalaris in its wander- 

 ings while in contact with the glass surface. This fact 

 alone would he. prima facie evidence of its having some 

 organ ada])ting it to auto-locomotion, and that in a par- 

 ticularly striking manner. The same simple aid will 

 also show that if one extremity of the prismatic bodv of 

 the Nitzschia should become detached by shaking from 

 contact with the side of the bottle, leaving but one end 

 adherent, the end in contact still may have sufficient 

 motive power therein to propel itself along the glass, 

 and when a Nitzschia is thus moving around, it can be 

 followed for hours, if the ol)server is so disposed. 



This is the simple character of an initial study that 

 might have been made by Leewenhoeck in his day, with 

 credit to himself for whatever his observing mind might 

 have noted in relation thereto. If now, however, the 

 conditions under which we view the Nitzschia be modi- 

 fied, w(> may find a new series of phenomena that would 

 have been totally overlooked in the experiment noted 

 above. If during the study we transfer a dij) of the dia- 

 tom material covering some of the Nitzschias to a glass 

 slip, and cover the same with a cover glass and view the 

 living frustules with the aid of a 1-6 objective, then the 

 peculiarities of locomotive and motile effects may be very 

 readily observed. A close study will verify the fact that 

 the Nitzschia has a distinct movement; not merely of 

 profjjression or change of place in a rectilinear path, but 



