PHENOMENA ACCOMPANYING FERTILIZATION 547 



parallel with each other and the final daughter nuclei fuse 2 by 2. 

 The cleft in the cell disappears and an encysted Amoeba results 

 with two amphinuclei. Each of these nuclei divides twice and 

 eight spores are formed about the resulting eight nuclei (Fig. 228, 

 7, J). 



Autogamy appears to be characteristic of the Neosporidia among 

 the Sporozoa and the processes are fairly uniform in M^Tcosporidia, 

 Microsporidia and Actinomyxida. IMultinucleate cells are t.\T3ical 

 of the nutritive or vegetative stage and in some cases the nuclei are 

 dimorphic. Spores are formed endogenously and during the con- 

 tinued vegetative activity of the organism. The process was well 

 described by Schroder (1907) for Sphcpromyxa sahrazesi, a parasite 

 of the sea horse, where the multinucleate amoi'boid body of the 

 parasite contains two kinds of nuclei distinguishable by size and 

 structure. Within the protoplasmic body small areas become differ- 

 entiated from the surrounding cytoplasm. These areas, character- 

 istic of the Myxosporidia, each contain 2 nuclei, 1 of each kind 

 (Fig. 229, K-Q). With the development of the pansporoblast, 

 each nucleus divides in such order that 7 daughter nuclei finally 

 result from each, the 14 nuclei behaving as follows: 2 are destined 

 to degenerate as "reduction nuclei;" 4 become the centers of capsule 

 and shell formation; 4 become centers of polar capsule formation; 

 and 4 remain as germinal nuclei. The protoplasm of the pansporo- 

 blast divides into two halves {M) the sporoblasts, and each contains 

 6 of the nuclei, while the 2 degenerating nuclei remain outside. 

 The 6 nuclei are thus differentiated into somatic and germinal 

 nuclei 4 in each case going into somatic difterentiations of the spores 

 (shells, polar capsules and threads) and 2 presumably 1 of each of 

 the original 2 kinds, remain as pronuclei {N, 0, P). 



Many different obser^'ers have noted this binucleated stage of the 

 young spore, and the problem of fertilization in Myxosporidia 

 appears to be bound up with their further fate. Schroder believes 

 that they unite later and so complete the fertilization, a belief 

 which he was able to prove in a later publication (1910). Keys- 

 selitz (1908) working on Myxobohs ffeiffcri, likewise believed in 

 the union of an analogous pair of nuclei during either the final 

 stage of development of the spore or in the young animal immediately 

 after leaving the spore case (Fig. 229, A-J). Davis (1916) observed 

 the union of such nuclei in Sjihcerophora diviorpha but was some- 

 what skeptical of his own observations, but Erdmann (1911 and 

 1917) confirmed Schroder in actually observing the fusion. AwTr- 

 inzew (1909) on the other hand, working with Ceratomyxa dreyano- 

 psetfcE, belicA-ed that fusion or fertilization does not occur in the 

 spore stage but after the initial development of the young animal 

 (see also Kudo, 1924). When the latter has reached the stage with 

 4 nuclei, 2 of the nuclei become trophic while the other 2 become 



