384 Louise Hoyt Gregory 



thirus magna which he described as the only fresh water form 

 in the genus Conchopthirus, the remainder being parasitic in land 

 and fresh water molluscs. Since 1888 no mention of this form 

 has been made in any classification or investigation. 



In November, 1906, an infusorian was found in the laboratory 

 of Columbia University, in an infusion of horse manure which 

 had been standing for a month. It was identified by Professor 

 Calkins as Tillina magna, and because of its characteristic tongue 

 of cilia in the oral region, in addition to its general coating of 

 cilia, I have classified it in the order Holotrichida, sub-order 

 Trichostomina, family Chiliferidae, thus taking it from the family 

 Enchelinidae where Kent had placed it, also from the order Hetero- 

 trichida where Biitschli placed it as synonymous with Conchop- 

 thirus, and with Gruber classifying it as a type closely related to 

 Colpoda and Paramecium. 



Because of its rarity and unusual power of reproduction, result- 

 ing in a rapid increase of numbers, and its apparent ease of culti- 

 vation in artificial surroundings. Professor Calkins suggested that 

 I study its morphological characteristics, its methods of reproduc- 

 tion, its reaction to stimuli, and the process of conjugation, in 

 fact, as much as possible of the processes taking place in the life 

 history, with the view of verifying the work of some previous 

 investigators, and of offering, if possible, further facts for the 

 discussion of such fundamental problems of biology as repro- 

 duction, artificial parthenogenesis, encystment, and the interrela- 

 tions of nucleus and cytoplasm. I wish to express my thanks to 

 Professor Calkins for his helpful suggestions and criticism through- 

 out the course of my work. 



In November, 1906, two strains were started from the wild 

 material. In January, 1907, I endeavored to find more wild 

 stock" in the original culture jar, but was unsuccessful. The 

 entire stock had disappeared. For two years I have made and 

 examined cultures, but in no case have I found the organism. 

 Gruber, in his early article, mentioned the fact that the organism 

 remained in the medium for only a short time, disappearing on 

 the appearance of other protozoan forms. This would accord 

 with Peters' idea of a gradual succession of forms in a protozoan 



