552 MAYOR. 



species. As the species is a new one, it has been named Ceratomi/xa 

 acadiensis. 



The only detailed observations on the life-histor>' of a disporous 

 form, since the paper of Doflein ('98), are those of Awerinzew (:08, 

 : 09) on Ceratomyxa drepanopsettae Awer. Awerinzew confines his 

 observations in the main to the stages leading to the formation of the 

 spores. He found that a binucleated stage of the myxosporidium, 

 in which the two nuclei were exactly alike, was followed by a stage 

 in which there were four nuclei, two of which were entirely trophic 

 in function, while the other two formed, by division, microgametes 

 and macrogametes. After a reduction in the chromatin of their 

 nuclei, first the protoplasm and then the nuclei of a macrogamete and 

 a microgamete fuse. This condition differs fundamentally from the 

 conditions in the Polysporea found in Sphaeromyxa sabrezesi by 

 Schroder (:07) and in M^xobolus pfeifFeri by Keysselitz (:08), where 

 a fusion of the germ-nuclei occurs in the fully formed spores. 



The writer has made a careful stud\- of the very early stages of the 

 myxosporidium and of the later stages in the spore formation of C. 

 acadiensis in order to extend and to verify in another species of Cera- 

 tomyxa Awerinzew's observations. He has found that in C. acadien- 

 sis — as was conjectured by Awerinzew for C. drepanopsettae — a 

 stage occurs with a single nucleus and that this nucleus divides into 

 two nuclei, which, however, differ from each other in size, staining, 

 reaction, and function. The writer, then, has found that there occurs 

 in C. acadiensis, even in the binucleated stage, the differentiation of 

 the nuclei which Awerinzew found first in the stage with four nuclei. 



Schroder (:07) has described the fusion of the two nuclei in the 

 sporoplasm of the full\' formed spore, and finds there the caryogamy 

 of the life-cycle. On the other hand, Awerinzew (:09), who has 

 found a reduction of chromatin followed by a fusion of nuclei in the 

 early stages of spore-formation in Ceratomyxa depanopsettae, believes 

 that the two nuclei in the germ of the spore do not fuse. 



Experiments were made calculated to ascertain whether or not 

 there occurred a fusion of the two germ nuclei in the fully formed spore 

 when this had remained for a length of time in the intestine of a host 

 fish. These experiments have, however, been unsuccessful, owing 

 probably to the spores used not being ripe. for transference to the 

 intestine or to the conditions of the experiment not being those required 

 for the continued life of the parasite. 



It may, howe\'er, be said that the constant occurrence of the two 

 germ nuclei side by side throughout the process of spore formation 

 suggests a later fusion rather than a separation. 



