THE BOTTLE ANIMALCULE, FOLLICULINA. 275 



RESPONSES TO SOLIDS. 



On emerging from the old tube the swimmer may not at once 

 swim toward the light but glide along on the leaves of Elodea; 

 such rapidly gliding Folliculina suggest planarian locomotion; 

 they seem investigating the surface by bending in and about 

 amidst diatoms and detritus and crawling over complex surfaces 

 as if attracted by contact. After swimming to the sides of a 

 vessel the Folliculina is markedly affected by contact, often at 

 once ceasing to swim and beginning to glide along the surface 

 of whatever nature it may be; but this adjustment to the surface 

 does not necessarily dominate for long, as the animal may sud- 

 denly swim free again for a short distance away from the surface 

 to return again. In this way it is a gradual process of coming and 

 going that finally results in the arrest of all motion on the surface 

 of future attachment of the new cases. When arrested by a surface 

 the animal abruptly changes form, frequently becoming spherical 

 or bottle-shaped. In some cases the body is markedly flattened 

 out against the surface and the form may be that of a pocket 

 flask some two times as wide as thick. In gliding as in swimming, 

 Folliculina may advance in jerks, or abrupt changes at very short 

 intervals. 



While the free swimmer comes to rest and adheres to the sur- 

 faces of leaves, paper, glass and porcelain as well as rough wood 

 there are some surfaces that are less available as indicated by 

 the few tubes formed on the resinous parts of the pine strips 

 above referred to, and by the failure of the following experiment. 



August 5, in a region where Elodea was nearly black with 

 tubes of Folliculina and many w r ere also present upon Potamo- 

 geton, plates of wax "foundation" as used by apiarists were 

 suspended in wooden frames so as to float just above the Elodea 

 in five to six feet of water. In six days but three or four very 

 young tubes were found on both surfaces of the two sheets of 

 wax, though the tubes were scattered over the narrow wood 

 frames. Ten days later the tubes were more numerous on the 

 wood, but only a dozen were on the wax. 



Though these experiments were tried too late in the season to 

 get a marked attachment of free swimmers yet it shows that the 

 small area of wood w r as more effective than the greatly larger 



