Miscellaneous. 305 



The little sphere of plasma then exhibits two nuclei ; as these 

 continue to divide, we soon have a sphere containing some ten of 

 them. The sphere itself next segments into two secondary masses 

 or sporoblasts, which remain united by the envelope of the primary 

 sphere. Each of these incloses a certain number of nuclei ; we 

 shall see further on that my observations do not permit me to deter- 

 mine whether the number is in reality four or only three, as was 

 found by Biitschli. 



However this may be, the nuclei which do not enter into the con- 

 stitution of the sporoblasts remain unemployed, and we subsequently 

 find them in a little mass of plasma which persists at the side of 

 the sporoblasts within the envelope of the primitive sphere. 



We now have to consider the phenomena presented by the sporo- 

 blast up to the complete formation of the spore. 



We first see the plasma (in the forms with two polar capsules) 

 divide into three little unequal masses, two smaller and one larger, 

 as has already been described by Balbiani and Biitschli. In the 

 two former the polar capsules will take their origin : the third will 

 become the plasmic mass of the spore. Each of the smaller masses 

 contains a nucleus, and before long we see, usually in the neigh- 

 bourhood of this nucleus, a little rounded vacuole arise, which 

 appears like a clear space and is distinguished from the plasma by 

 the absence of granulations. At some point of the wall of the 

 vacuole there arises a kind of little bud of protoplasm, which grows 

 out into the vacuole, driving back round its sides the substance with 

 which the vacuole is filled ; in this way after a certain time we get 

 a little pyriform body surrounded by a clear stratum, formed by the 

 contents of the vacuole, and united by a sort of pedicle with the 

 remainder of the plasma, from which it does not differ in the least 

 in appearance. The pedicle is gradually constricted, and the little 

 pyriform body soon becomes free ; meantime it has become sur- 

 rounded by a membrane, and a filament has developed in its inte- 

 rior. The latter clearly arises from the protoplasm of the bud ; but 

 I have not been able to follow the process of its formation. 



Around the polar capsule which has thus been formed we find 

 the remains of the globule of protoplasm which gave it birth and 

 the nucleus which the latter contained. The nucleus in most cases 

 remains attached to the capsule ; but sometimes it may separate 

 from it and be included in the plasmic mass of the ripe spore. In 

 a previous paper * I had considered these nuclei as belonging to the 

 latter, and had assigned to them a different origin ; the study of 

 their evolution and especially the use of better methods now enable 

 me to rectify my mistake and give to the facts their true significa- 

 tion. 



The polar capsules during their formation have no fixed direction ; 

 it is not until later on that they orientate themselves and take up 

 their definite position. 



* Thelohan, " Sur la constitution des spores des Myxosporidies," Comptes 

 Rendus, December 9, 1889; " Conti'ibutions a l'e'tude des Myxosporidies," 

 Annales de Micrographie, February 1890. 



