108] 



The Classification of Lower Organisms 



Scytomonas pusilla Stein {Copromonas subtilis Dobell) occurs in the intestines 

 of frogs and toads. When cast out with the feces, it exhibits conjugation as a pre- 

 liminary to encystment (Dobell, 1908). 



Family 4. Anisonemida [Anisonemidae] Kent Man. Inf. 1: 429 (1880). Families 

 Pernamina and Anisonemina Biitschli in Bronn Kl. u. Ord. Thierreichs 1 : 824, 828 

 (1884). Family Peranemaceae Senn in Engler and Prantl Nat. Pflanzenfam. I Teil, 

 Abt. la: 178 (1900). Family Heteronemidae Calkins Biol. Prot. 285 (1926). Each 

 cell of these colorless organisms bears one conspicuous anterior flagellum; most of 

 them bear also a less conspicuous trailing flagellum. The trailing flagellum of Pera- 

 nema is grown fast to the cell membrane, and is detected only with difficulty (Hall, 



Fig. 21.— a, Menoidium incurvum. b, c. Stages of mitosis in Menoidium incurvum 

 X 2,000 after Hall (1923). d, e, Peranema trichophorum. i, Stage of division in 

 Peranema trichophorum after Hall (1934). g, Anisoncma truncatum. h, Ento- 

 sipon sulcatum, i-m, Vacuolaria viridis: i, cell; j, neuromotor apparatus after Fott 

 (1935); k-m, stages of mitosis x 2,000 after Fott, op cit. x 1,000 except as noted. 



