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NEOSPORIDIA 



ORDER III. SARCOSPORIDIA Biitschli, 1882. 



Definition. — Neosporidia in which the young trophozoite is, with 

 rare exceptions, found in the muscle-fibre of warm-blooded animals. 

 Spore-formation commences early, and proceeds during the whole 

 growth of the trophozoite, which may attain a very large size, when 

 it is covered by two coats, the inner of which is prolonged internally 

 through the parasite, dividing it into a series of chambers. 



Remarks. — The Sarcosporidia, discovered by Miescher in 1843, 

 are very common parasites, and in the form of Sarcocystis tenella 

 maybe seen by the practitioner in the tropics in meat sent as food 

 to gaols and hospitals. 



Two families are known : {1) Sarcocystidce, (2) RhinosporidiidcB. 



1. Sarcocystidse Poche, 1913. 

 Definition. — Sarcosporidia found in muscle fibres, and divided 

 into chambers by septa. 



Sarcocystis Lankester, 1882. 

 Synonym. — Gastrocystis Chatton, 1910. 



Definition. — Sarcocystidse with outer radially striated and inner 

 homogeneous coat and poles of undifferentiated protoplasm. 



Type Species. — Sarcocystis miescheriana Kiihn, 1865. 



Though a common parasite, its life-history is by no means well 

 known. The youngest form is the trophozoite described by 

 Bertram, which lies in a muscle-fibre, and consists of cytoplasm 

 united by a cuticle, and containing several mononuclear pansporo- 

 blasts. The next stage is more advanced, for in this the troph 3zoite 

 has grown considerably, and now consists of two coats — an outer, 

 radially striated, and an inner, homogeneous, which is prolonged 

 externally into filaments and internally into a series of septa, 

 marking out chambers, each of which contains one pansporoblast. 

 Internal to this coat is a layer ol cytoplasm forming the endoplasm 

 of the^parasite. 



Fig. 187. — Sarcocystis tenellcs bubali: Young Form. 



The poles of the parasite consist of undifferentiated endoplasm, 

 and form the areas of growth of the young trophozoite. The pan- 

 sporoblast breaks up into a large number of spores. 



The third stage is reached When the parasite has grown so much 

 that it has stretched the muscle-fibre, in which it is lying, into a thin 

 sheath covering it, and therefore now appears to lie between the 

 muscle-fibres. The endoplasmic layer extends all round the interior 

 of the parasite, so that the pansporoblasts are formed from the whole 

 periphery, and therefore the youngest forms are in this position, 



