THE BOTTLE ANIMALCULE, FOLLICULINA. 28 1 



Observations upon free swimmers and those making cases 

 throw light upon the above groupings of the cases. The factor 

 of importance in addition to the responses to light and to foreign 

 objects seems to be the secretions put out by the free swimmers. 



That the swimming forms may put out considerable amounts of 

 invisible and adhesive secretions was shown in various indirect 

 ways. Thus when india ink is rubbed up with the water in which 

 the Folliculina swims, the presence of a secretion following the 

 swimmer is evident. On the addition of granular carmine, 

 swimmers were seen followed by long strings of granules and 

 some included diatoms trailing behind the Folliculina four times 

 its greatest length. 



Again when the swimmers press upward into drops of water 

 spreading up onto the edges of a procelain dish they get into 

 water films of great thinness and here there seems a distinct 

 film of bluish green material which remains on the porcelain after 

 the Folliculinas have been removed. 



That this secreted substance must be very adhesive is to be 

 gathered from several cases in which a motile form came into 

 contact with the larva of some aquatic insect, apparently dip- 

 terous. These larvae are relatively large so that the Folliculina 

 glides up and down and around the larva, whose diameter is 

 much greater than the length of the Folliculina. The tendency 

 of the Folliculina to remain attached to the surface of the larva 

 while gliding all over it was most pronounced and its adhesion to 

 it very strong, for the insect violently coiled in figures of eight 

 and struggled with its legs without dislodging the Folliculina. 

 When after many minutes the Folliculina left the insect a strand 

 of slime was seen stretched between; presently when the insect 

 came near but not into contact with the Folliculina they stuck 

 together and the gliding over the surface \vas resumed. 



Some motile forms about to make cases in the film of water 

 rising on the edge of a watch glass were bound together by fine 

 threads of slightly greenish material. Observations of motile 

 forms about to settle down and secrete the case, shows that they 

 come to rest gradually, moving in ever smaller areas and often, 

 as it were, skating about on the posterior end and then flattening 

 the whole body against the substratum. One may become at- 



