428 THE PROTOZOA 



a single nucleus and grows up into the adult amoeba-like phase. Sexual phe- 

 nomena have not been observed, though their occurrence is indicated by the 

 development described. Chatton considers that the parasite has resemblances 

 to Amcebspa, Mycetozoa, and Sporozoa. 



Chytridiopsis, Schneider. Leger and Duboscq (823) describe several species 

 parasitic in the intestine of insects, and have followed out the development of 

 G. socius. The youngest form is a minute amcebula which penetrates into 

 an epithelial cell, and grows, with multiplication of its nuclei, to form a 

 plasmodium or schizont, which then divides up to form a mass of uninucleate 

 " schizozoites," each one at first crescent-shaped, then amoeboid. The 

 schizozoites are set free in the intestine, and penetrate other cells ; they either 

 grow" into schizonts, which repeat the process of schizogony, or into gameto- 

 cytes. Certain schizozoites grow within the cells without multiplication 

 of the nuclei till they attain a diameter of about 10 /* ; then the nucleus divides 

 rapidly, and a number of microgametes are formed. Other schizozoites become 

 macrogametes, which are about 8 /* in diameter and appear to be fertilized 

 each by a microgamete. The nucleus of the zygote divides into a great 

 number of nuclei, three or four of which travel to the 

 surface of the spherical body and form a cyst- 

 envelope ; the remaining nuclei retain their central 

 position, and the body of the zygote divides into . uni- 

 nucleate spores. In this way resistant cysts are formed 

 containing a large number of spores, each containing 

 a single nucleus and a vacuole. The cysts are cast out 

 of the body and infect new hosts. 



Leger and Duboscq consider that Chytridiopsis may 

 be allied to the Microsporidia ; but having found no 

 polar filament in the spore, they prefer to regard it as 

 FIG. 179. Spores of having affinities with Mycetozoa.* 



Gastrocystis gtiru- The genera Amcebidium and Siedleckia were held 



thi. After Chatton formerly to constitute a distinct order of the Sporozca, 



(819). which was named the Exosporidia. Amcebidium has 



been shown clearly by Chatton (817) to be an organism 



of the nature of a fungus ; while Siedleckia is now generally referred to the 

 schizogregarines, as suggested by Minchin (589) ; see Dogiel (606). Compare 

 also Capillus intestinalis, Granata, parasite of the intestine of Millepedes. 



Affinities of the Neosporidia. It is sufficiently apparent, from the 

 structure and development of typical examples of any order of this 

 subclass, that their affinities are wholly with the Sarcodina. In the 

 case of many of the more primitive forms, it is an open question 

 whether they should be classed in the Neosporidia or in one of the 

 orders of the Sarcodina. Comparing them with the Telosporidia, 

 it is seen that the two characteristics of that subclass which indi- 

 cate affinities with the Flagellata are absent altogether in the 

 Neosporidia namely, the possession of flagellated swarm-spores or 

 gametes, and the definite, gregarine-like body-form of the adults. 

 No flagellated stages are known to occur at any period of the life- 

 history in any member of the Neosporidia, and the body-form of 

 the adult in this group is typically that of an amoeba. Many of the 

 Myxosporidia might almost be regarded as parasitic amoebae with 

 a peculiar type of reproduction. Even more remarkable is the 



* It is not clear on what grounds Schepotieff (269, p. 516) considers Chytridiopsis 

 to be a Flagellate. 



