1905.1 NATURAL SCIENCES OF PHILADELPHIA. 89 



THE MOVEMENTS OF GREGARINES. 



BY HOWARD CRAWLEY. 



For the proper comprehension of the movements displayed by gre- 

 garines, it is advisable first to consider the form and anatomy of the 

 animals. In a species like Porospora gigantea Van Beneden the ratio 

 of length to breadth is 50-1, whereas Lophocephalus insignis Aime 

 Schn. is nearly spherical. It is obvious that the first of these two 

 species can display movements of contortion which the second cannot. 

 These are extreme cases, but gregarines may roughly be divided into 

 long, slender and short, stout species, and in a discussion of their move- 

 ments it is well to keep in mind the limitations to flexibility imposed 

 on the latter merely on account of their shape. 



Further limitations are imposed by the anatomical structure. From 

 without inward, a polycystid gregarine displays epicyte, sarcocyte, 

 myocyte and entocyte. The epicyte is a cuticular layer, the function 

 of which is protective. It is always present, and varies considerably 

 in thickness in the different species. The sarcocyte is a layer of clear 

 protoplasm which, in a typical case, is continuous over the entire ani- 

 mal. This condition exists in such genera as Gregarina, Stenophora 

 and Amphoroides. Frequently, however, the sarcocyte is lacking, 

 except for the septum, which it constitutes, and in the immediately 

 adjacent parts. These two layers may collectively be termed the 

 ectosarc. 



The myocyte is described by some authors as a part of the ectosarc; 

 by others as a part of the endosarc (entocyte). It is made up of a 

 layer of fibrils. Of these, the more conspicuous encircle the animal 

 in a slightly spiral direction. The circular fibres are joined together by 

 longitudinal and diagonal connectives, the whole system forming a net. 



The entocyte of gregarines is probably much like that of other 

 protozoa. It is composed of soft, distinctly alveolar protoplasm, 

 liberally provided with the so-called granules of reserve. 



It will be seen from the above that the ectosarc of gregarines may 

 vary greatly in thickness. We may have a species in which both the 

 component layers are thick. On the other hand, the epicyte may be 

 thin and the sarcocyte absent. We probably have here an explanation 

 for the difference in the rigidity of gregarines. Some species, such as 



