110 PROCEEDINGS OF THE ACADEMY OF [1898. 



OBSERVATIONS ON ERRANT FRUSTULES OF EUNOTIA MAJOR. 

 BY T. CHALKLEY PALMER. 



The diatom Eunotia major Rab. occurs in some abundance in the 

 uplands of Delaware Co., Pa., though appearing to flourish only in 

 the basins of such springs as are well-shaded at all seasons. In these 

 springs it is often present in profusion, forming masses of clean, 

 brownish filaments attached to the sides of the pools, and by prefer- 

 ence to submerged wood. The filaments grow to a length of ten 

 centimeters, and vary in breadth from 0.036 mm. to 0.200 mm. 

 in accordance with the length of their constituent cells. These fila- 

 ments intertangle in such manner as to afford cover for numerous 

 protozoa, and for such diatoms as Surirella, Nitzschia, Pinnularia 

 and Navicula. Eunotia lunaris Grun. also frequently occurs in pro- 

 fusion in the same company. 



In making a gathering of the filaments for study, it is well to be- 

 gin by washing them free from all loosely adherent matters, such as 

 sand, mica and clayey flocculence. They are then placed in a clean 

 bottle which has been filled with water from the spring. A short 

 exposure to diffused daylight will cause the diatoms to rise to the 

 top, buoyed up by a multitude of oxygen bubbles entangled among 

 them, and to free themselves from a further portion of mineral mat- 

 ter, which will at once subside, and may be rejected by decantation. 



An examination of the gathering under the microscope will usu- 

 ally reveal, besides the filaments, a certain number of frustules, 

 either isolated or in groups of two or three, moving about in a slow 

 and erratic manner. In the course of two or three days, if all goes 

 well, the proportion of moving cells will have increased ; and from 

 day to day, conditions permitting, the long filaments will progres- 

 sively separate, until frequently the whole gathering ends by resolv- 

 ing itself entirely into isolated cells and short sections composed of 

 two, four or even six cells, all in a state of lively locomotion. 



Conditions favoring production of errant frustules. — The prime 

 requisite for any extended study of the gathering is the preserva- 

 tion of the diatoms in a healthy condition. The best results have 

 followed with Eunotia major when the clean filaments were kept in a 



