136 BRUCE D. REYNOLDS. 



explanations. It seems most reasonable to think of it as being 

 due to a difference in molecular structure, or ionization; at least 

 the sudden violent shattering is suggestive of an electrical phen- 

 omenon. The inability of one organism to fuse with a proto- 

 plasmic fragment of another, does not imply that the two organ- 

 isms concerned differ structurally, nor does cross-fusion indicate 

 that no morphological differences exist. In either case the 

 animals involved may or may not be identical in size, structure 

 and rate of fission. 



Maupas ('88, '89), in studying the effect of temperature on the 

 fission rate of infusoria, arrived at the conclusion that under 

 given conditions the fission rate remains the same, and that 

 inherited variations do not exist. Regardless of the important 

 bearing this statement has on the theory of evolution, there was 

 but very little interest exhibited until some time after the publi- 

 cation of Johannsen's ('03) results, in which he enunciated his 

 concept of genotypes. Since then workers in various fields have 

 investigated the subject of Heredity and Environment. Like 

 Maupas, most of them have obtained evidence which seems to 

 emphasize the "fixity" of species. Among these might be 

 mentioned: Johannsen ('09, 'u) working with beans, Hanel 

 ('08) and Lashley ('15) with Hydra, Jennings ('08, '09, '10) with 

 infusoria, Ackert ('16) with Paramecium, and Jollos ('21) with 

 infusoria. However, recently Barber ('07) working with bac- 

 teria, Jennings ('16) with Difflugia, Hegner ('19) with Arcella, 

 Root ('18) with Centropyxis, Middleton ('15, '18) with Stylon- 

 ychia, Erdmann ('20) with Paramecium, and others, have appar- 

 ently been able to demonstrate that variations do take place 

 among organisms reproducing asexually and as Erdmann ('20) 

 says: 'The rigid conception of the genotype does not hold true 

 for protozoa." 



To enter a field filled with so much conflicting evidence, armed 

 with a new method, was an especially attractive undertaking. 

 The experiments were planned with the idea of duplicating, so 

 far as possible, the various conditions to which protozoa have 

 been subjected by others. The only new factors employed were 

 the method of determining variations which might arise, and a 

 little different way of preparing the culture medium. 



The results obtained seem to combine the two diverse opin- 



