NEOSPORIDIA 95 



Of the three suborders of the Cnidosporidia, the Myxosporidia have 

 two or four pole capsules in the spore, the Microsporidia one, and the 

 Actinomyxidea three. The latter group also differ from the other two in 

 respect of the germs, as mentioned above. 



Myxobolus (Myxosporidia, Fig. 8i). Large syncytia in the tissues 

 of various freshwater fishes. Some species are harmless, others 

 dangerous pests. 



Nosema (Microsporidia). The syncytium early breaks up, first into 

 binucleate forms and finally into single sporoblasts. In the intestinal 

 epithelium of insects. A serious pest of the silkworm, causing the 

 disease known as pebrine, and of the bee. 



Sphaeractinomyxon (Actinomyxidea). The whole body is reduced 

 to a single pansporoblast, as in all members of the suborder. The 

 spores are without the spines found in related genera. In annelids. 



Order HAPLOSPORIDIA 

 Neosporidia whose spores possess cases with a lid, but have no pole 

 capsules. 



This order contains certain parasites which infest aquatic in- 

 vertebrates. They are perhaps derived from the Cnidosporidia by 

 loss of the pole capsules. 



Haplosporidium, parasitic chiefly in annelids, is the typical genus. 



Order SARCOSPORIDIA 



Neosporidia whose spores do not possess cases or pole capsules. 



These organisms are tubular syncytia with a radially striped ecto- 

 plasm, parasitic in the muscle fibres of mammals, and reproducing by 

 simple, sickle-shaped spores. 



Sarcocystis (Fig. 82). In various mammals, occasionally in man. 



Class CILIOPHORA 



Protozoa which, at least as young, possess cilia; are never amoeboid; 

 if parasitic are very rarely intracellular ; nearly always possess a mega- 

 nucleus; and do not, after syngamy, form large numbers of spores. 

 This class, though some of its parasitic members are of compara- 

 tively simple structure, contains the most highly organized Protozoa. 

 Facts concerning sundry of the organs and processes in its members 

 (the ciliary apparatus, pp. 13, 14 ; the contractile vacuole system, p. 16 ; 

 the nucleus, p. 21 ; conjugation, p. 28; etc.) have been stated above. 

 The life history, except for the remarkable process of conjugation 

 undergone by most of the class, is relatively uncomplicated. In 

 particular, though the nuclear peculiarities of the typical members 

 of the group render inevitable certain special features in the metagamic 

 divisions, there is no true sporogony. 



