NliUKOSPOrvIDlUM. 97 



process which in so many groups of animals is known to 

 result from indulgence in a parasitic mode of life. 



For the present the Neosporidia may be divided as follows : 



1. Cnidosporidia (Doflein), with polar capsules. 



Myxosporidia^ e.g. Myxobolus, Sphgerospora. 

 Microsporidia, e.g. Glugea^ Pleistopliora. 

 Actinomyxidia, e.g. Hexactinomyxon. 

 ? Sarcosporidia, e.g. Sarcocystis. 



2. Haplosporidia (Caullery and Mesnil), simpler forms than 

 the above, without polar capsules. 



Oligosporulea, e.g. Bertramia, Haplosporidium. 

 Polysporulea, e.g. Rliiuosporidium, Neurospori- 

 dium. 



►Summary. 



The parasite begins its life-cycle as a round or oval gymno- 

 spore or amgebula in the nervous system of the host (figs. 3 

 and 4). 



The am£ebula3 cause a degeneration of the nerve-tissue 

 immediately around them, and come to lie within cavities, 

 one amaebula in a cavity, or several (fig. 5). 



The amasbula becomes a multinucleate trophozoite, either 

 by enlarging and undergoing nuclear division, or by coales- 

 cence with other ameebulEe or young trophozoites, or by a 

 combination of both processes (figs. 6, 7, 8, 9). 



The capsule surrounding the parasite is ill-defined, and is 

 probably formed by the host (fig. 12, etc., cps.). 



The trophozoite segments into uninucleate pansporoblasts 

 (figs. 10, 11), each of which enlarges and becomes a spore- 

 morula. 



The spore-morula gives rise to many small spores (figs. 

 12, 13), and after the liberation of these, there remains amass 

 of granular protoplasm, with residual nuclei (figs. 15, 16, 17). 



The infection probably spreads through the nervous system 

 of the host by the migration of the amaebulte and trophozoites. 

 The mode of cross-infection from host to host is not known. 



It is proposed to divide the Haplosporidia into the Poly- 



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