274 E - A - ANDREWS. 



In a very small drop of water the Folliculina may go back and 

 forth again and again like a trolley car, reversing at each end of 

 its short trip. One individual with a fixed black spot on the 

 anterior end was seen to go forward and backward and to spin 

 about its transverse axis without revolving about its long axis. 



RESPONSES TO LIGHT. 



It is very striking to see the completeness with which light 

 determines the distribution of the swimming Folliculina in 

 aquaria. If in an opaque dish the tubes are all made on the side 

 most illuminated, towards the window in a room, or if in a square 

 glass vessel all tend to crowd to the angle nearest the strongest 

 light window. Watching the swimmers we see that they go 

 rapidly toward the light and only turn back upon striking an 

 obstacle such as the side of the dish when they may swim away 

 for a distance soon to return and eventually to remain nearest 

 to the light. The new tubes are then built along the side toward 

 the light and most all are very near or at the surface of the water 

 unless some irregular reflection determines the formation of two 

 bands, one near the surface and one deeper down, but while 

 the densest crowd is close to the surface, tubes are made an inch 

 and a half below the surface in a scattered arrangement. New 

 tubes formed on strips of paper and glass slides at the side of the 

 dish were removable for study and preservation. When the 

 aquarium is placed on the floor and lighted largely from above, 

 many tubes are formed on the surface of the water, either on 

 floating objects as cover glasses, pieces of paper, leaves, etc., or 

 merely on the surface film. In this way new tubes with the con- 

 tained animals were obtained free from all solid substratum and 

 excellent for sections and other manipulation. 



By placing an opaque paper with central hole over the dish con- 

 taining the Elodea and old Folliculina the new formed swimmers 

 were concentrated to the center of the dish and could be taken 

 out with the pipette or later taken up as floating colonies away 

 from the sides of the vessel and in a limited area. 



While most all of the swimmers collect toward the light some 

 may form tubes on the sides of the vessel away from the light, 

 but these are much in the minority. In a watch-glass the 

 swimmers go at once to the side whence the light comes. 



