FERTILIZATION BY AUTOGAMY 143 



fertilization nuclei finally result, each of which divides again, this time 

 with the long axes of the spindle parallel with one another; the final 

 daughter nuclei which are formed fuse two by two, the cleft in the 

 cell disappears, and an encysted ameba results with two fertilized 

 nuclei. Each of these nuclei divides twice, and eight spores are formed 

 about the eight resulting nuclei. Hartmann ('07) mentions a similar 

 process of autogamy in the case of an ameba from the frog and in one 

 of the free-living Umax forms, but describes a quite dissimilar process 

 in Entameba tetragen'a. 



In these cases, therefore, there is a concentration of the Idiochro- 

 midia in secondary nuclei which then undergo so-called maturation 

 processes. A still greater complexity is shown by Ameba proteus, 

 where, according to the observations of Calkins ('07), there is no 

 formation of diffused idiochromidia, but the secondary conjugating 

 nuclei are formed directly from chromatin granules within the primary 

 nuclei, which, prior to this stage, had divided repeatedly until about 

 70 are present. These secondary nuclei next fuse two by two in the 

 cytoplasm and give rise to spore-mother cells (sporoblasts), of which 

 there may be as many as 250 within one parent organism (Fig- 60), 

 while at least one of the primary nuclei remains unused and finally 

 degenerates in the cell. In Ameba proteus, therefore, the organism 

 forms not one spore-mother cell, as in the parasitic amebse, but many 

 such spore-forming centres. 



In all of the above cases of autogamy, we have to do with the fusion 

 of chromatin materials which at one time or another were parts of the 

 same nucleus of the same cell. In all of them, with the exception of 

 the free-living Ameba Umax and the parasitic Entameba histolytica, 

 where further observations are much to be desired, the union of the 

 "gametic" nuclei does not take place until after two or more divisions 

 of the primary or secondary nuclei; that this fact has some signifi- 

 cance cannot be doubted, but there is no inkling as to what the 

 significance is, unless, indeed, it is evidence of an earlier eamete- 

 forming stage, autogamy thus being, as Hartmann ('09) suggests, a 

 degenerative rather than a pri;nitive phenomenon. 



With the myxosporidia the process is much more complicated, 

 involving the formation of vegetative and germinal nuclei. It is well 

 described by Schroder ('07) for the case of a parasite of the seahorse, 

 Spheromyxa labrazesi, where the multinucleate ameboid body of the 

 parasite appears to contain two kinds of nuclei distinguished by size 

 and structure. Within this protoplasmic body small areas become 

 differentiated from the surrounding matrix. 'These areas character- 

 istic of the myxosporidia, termed pansporoblasts (Gurley), contain 

 two nuclei, one of each kind (Fig. CI, K, Q). With development of 

 the pansporoblast each nucleus divides in such order that seven 

 daughter nuclei finally result from each, the fourteen nuclei being 



