MORPHOLOGY AND TAXOXOM) OF THE SPOROZOA 535 



drawn out into attaching organs in the form of filaments, hooks, 

 anchors and knobs. The outer surface is often definitely ribbed, 

 the ribs running longitudinally from end to end of the body. The 

 furrows between the ribs are filled with a gelatinous material derived 

 from a second layer, also lifeless, of the cortex and termed by 

 Schewiakoff the gelatinous layer. The third zone of the body 

 wall is formed by the living ectoplasm which, with the possible 

 exception of Stomatophora coronata described by Hesse (1909) as 

 possessing a mouth, peristome and cell anus, forms an unbroken, 

 living, protoplasmic membrane. The endoplasm, or fourth zone, 

 finally, forms the bulk of the organism and contains the single 

 nucleus, usually provided with a large endosome. Paraglycogen, 

 volutin granules and other products of living activity make the endo- 

 plasm dense and homogeneous so that it appears white by reflected 

 and black by transmitted light. Crystals of protein-like substance 

 are present in many cases, also crystals which have been identified 

 as calcium oxalate. Between endoplasm and ectoplasm, finally, a 

 system of myonemes may be found in some cases. These, accord- 

 ing to Roskin and Levinson (1929), lie in definite canals. The 

 presence of myonemes led to the view that a special myocyte zone 

 is present in addition to the other zones. It is found, however, 

 that in addition to these longitudinal myonemes a second set of 

 circular myonemes is present, lying between the sarcocyte and the 

 endoplasm. A definite myocyte zone, therefore, is absent and 

 myonemes may be found anywhere in the cortex. In Zygocystis 

 conspicuous myoneme-like threads originate in the cortex near the 

 anterior end, become free in the posterior third of the body and as 

 free threads trail out behind the posterior end in characteristic 

 manner. 



The movement of gregarines has been variously interpreted. In 

 some cases, e. g., Clepsidrina munieri, the organism glides forward 

 without evident contraction of the body; in other cases, e. g., Mono- 

 cystis agilis, forward movement is accompanied by waves of peris- 

 taltic contraction and in still other forms there are more or less 

 spasmodic jerks from side to side. The smooth gliding motion, 

 according to Schewiakoff (1894), is due to the secretion of a gela- 

 tinous material from the sarcocyte which passes backward along the 

 grooves formed by the ridges of the epicyte. This gelatinous 

 material rapidly hardens on exposure to water, and fresh jelly 

 hardening in turn on this, forces the organism forward. On this 

 interpretation the myonemes play no part. Crawley (1902, 1905), 

 in connection with Stenophora juli and Echinomera hispida, holds 

 that the slime is not a cause but a result of movement and inter- 

 prets locomotion as due to the annular contraction of circular myo- 

 nemes, the organism moving in much the same manner as does a 

 snake. Sokoloff (1912) differs from both Schewiakoff and Crawley 



