THE SPOROZOA 



145 



with digitiform, appendages. It may be closely attached to the pro- 

 tomerite, or carried on a long neck, while variations in all types are 

 numerous (Fig. 12, E, F, G, p. 39). Under certain conditions, prior 

 to reproduction, the animal throws off the epimerite which may be left 

 in the cell-host, and drops into the lumen of the organ in which it 

 lives. Here it encysts, the protomerite and deutomerite forming one 

 spore-producing individual. As the attached and the detached stages 

 in the life-history of the Gregarine are each important, they have 

 received special names, the former 

 being known as a cephalont, the latter 

 as a sporont. 



Between the cortical ectoplasm and 

 the inner endoplasm there is a layer of 

 myonemes, or muscular fibrils similar 

 in all respects to those of the Ciliata 

 (Fig. 80). These are occasionally 

 found in the Haemosporidiida, but are 

 much more characteristic of the Gre- 

 garinida, where, except in the epimerite, 

 they form a network about the entire 

 animal. On the outside of this net- 

 work, according to Schewiakoff ('94), 

 there is, at times, a layer of gelatinous 

 matter apparently secreted by the ecto- 

 plasm, and this, in turn, is covered by 

 the membrane proper. The mem- 

 brane is longitudinally striated by rib- 

 like projections, while the canals or 

 furrows between them are filled with 

 jelly from the gelatinous layer below 

 (see Fig. 82, H}. Schewiakoff believes 

 that the active secretion of jelly in these furrows accounts for the 

 peculiar gliding motion of certain kinds of Gregarinida. In the region 

 of the epimerite, the membrane is plain, the ribs and furrows stopping 

 with the protomerite. The hooks or spines are formed from the 

 cortical plasm. 



In one group of Sporozoa, the Sarcosporidiida, the protoplasmic 

 body is inclosed in a peculiar pouch which appears to be a secretion 

 from the protoplasm rather than a true cellular membrane. The 

 mass slowly enlarges by regular growth until it reaches a considerable 

 length, in some cases several millimetres. It then undergoes spore- 

 formation. These organisms, known as Rainey's Tubes, are parasites 

 of sheep, swine, deer, horses, rats, etc., where they infest the muscle- 

 tissues, causing morbid symptoms, similar to those in trichinosis. 



Fig. 80. Schematic figure of the 

 myonemes of Clepsidrina munieri ; ni, 

 the myonemes. [SCHNEIDER.] 



