134 BRUCE D. REYNOLDS. 



DISCUSSION. 



Before entering into a discussion of the results obtained in 

 these investigations, it is perhaps advisable to show that the 

 method employed is sound, and that it offers some advantages 

 over the methods which have been utilized by others. As stated 

 in the introduction, this is the first time that the interactions of 

 protoplasmic masses have been used in studying the subject of 

 Heredity and Environment. It was not until the recent appear- 

 ance of the first article of this series that anything was published 

 concerning the fact that certain of the shelled rhizopods are 

 capable of reappropriating, by fusion, fragments of protoplasm 

 which have recently been detached from their cell-bodies. In 

 this paper it is clearly pointed put that "the severed fragments 

 are not recovered as food, but enter again immediately into the 

 protoplasmic structure of the cell-body." Later work has 

 strengthened the evidence for such a contention. In fact, the 

 findings in these experiments with A. polypora substantiate all 

 of the conclusions drawn from the work on Difflngia, except para- 

 graphs 3 and 5 of the general summary. 



In regard to paragraph 3: In Arcella, fusion has been observed 

 to occur at the ends of pseudopods, as well as along an extended 

 mid-region. This difference in behavior of the two genera may 

 be due to the difference in the nature of their pseudopodial forma- 

 tion. As to paragraph 5 : In six cases out of approximately 1,000 

 two enucleated fragments have been observed to fuse with each 

 other; though in such instances they were severed from the same 

 cell-body at the same time, and were almost in contact in the 

 beginning. 



In addition to the data on protoplasmic fusion given in Article 

 No. i : the "shattering" reaction is described in the introduction 

 of the present paper. This is the kind of reaction usually ob- 

 served when an organism made contact with a fragment severed 

 from a distantly related individual. It was found that in such 

 cases there was a mutual attraction between the organism and 

 the fragment even though their protoplasms were shattered 

 upon making contact. If the fragment came from a closely 

 related specimen fusion occurred. When a fragment of proto- 

 plasm was severed from a different genus (Dijflngia) and placed 



