THE ANIMAL PARASITES OF MAN 



there arise membranes in the interior of the body that form 

 anastomosing partitions, or rather a system of manifold chambers 

 of various sizes that do not communicate with one another 

 (fig. 58). These chambers are occupied by sickle or bean-shaped 

 bodies (sporozoites), or rather their stages of development ; fre- 

 quently, however, they .are empty, and this is particularly the 

 case in the central chambers of the large species. 



In the youngest Sarcosporidia (0-04 mm. in length) from the 

 muscles of the sheep one finds, according to Bertram, small 



FIG. 58. Transverse section of Sarcocystis 

 tenella, Raill. (from the oesophagus of Ovis aries). 

 38/1. (a) Marginal chambers filled with spores ; (b) 

 connective tissue of the ossophagus ; (c) muscles 

 of the ossophagus. 



FIG. 59 . Young 

 Sarcocystis tenella 

 of the sheep (0*047 

 mm. in length) 

 (after Bertram). 



roundish or oval cells (0*004-0*005 mm.), the nuclei of which are 

 half their size, and are embedded in a granular and apparently 

 protoplasmatic mass ; in somewhat larger, and therefore older, cylin- 

 ders, the investing membrane of which already presents both layers, 

 the cells have become larger (to 0*007 mm.) and are more sharply 

 outlined from each other (fig. 59). Taking their later condition 

 into account they may be considered as sporoblasts, for their 

 nuclei commence to divide ; finally they become isolated within 

 the chambers, the dividing partitions of which originate from the 

 granular protoplasm which is present between the sporoblasts ; 



