THE SPOROZOA 



which run from the anterior to the posterior end in waves of contraction 

 (Fig. 49, e and /), similar to the " euglenoid " movements of Gregarines 

 and Flagellates (see p. 181). During these contractile movements a fine 

 longitudinal striation of the body surface is to be observed, caused, 

 however, not by the presence of myocyte-fibrillae, but by the arrangement 

 of the superficial alveoli of the protoplasm in longitudinal rows (Schaudinn 

 [51rt]). In the second place, the sporozoite moves forward by a gliding 

 movement similar to that of Gregarines, and effected in a similar manner, 

 namely, by secretion of a gelatinous thread which pushes the little animal 

 forward as it is formed (Fig. 49, a and b} ; movements of progression of 

 this kind alternate with movements of flexion, and after having traversed 



1$ (I 



spz 



Fio. 49. 



Movements of living sporozoites and merozoites of Coccidium sch>il>er>-/i, Schaud. (par. 

 Lithobius forficatus). After Schaudinn [51]. <>, 1>, forward progression of a sporozoite by secretion 

 of a gelatinous thread (g.s), which is attached to foreign objects, and pushes the little creature 

 forwards. In b the portion of the thread between two foreign bodies has snapped and shrivelled 

 up. c, a merozoite in forward progression. The arrow on the left shows the direction in which 

 the merozoite is moving ; those on the right, the direction in which the gelatinous substance 

 secreted by it is flowing backwards to form a filament, d-y, penetration of an epithelial cell 

 by a sporozoite. H.C, host-cell ; N, its nucleus ; sp.z, sporozoite. 



from five to seven times its own length, it comes to a stop, bends its 

 body three or four times, and starts again. Thus the sporozoite greatly 

 resembles in its movements and general appearance a minute Gregarine. 



By means of its progression the sporozoite reaches an epithelial cell, 

 and presses its anterior pointed end into it (Fig. 49, d). The opening is 

 widened by its euglenoid contractions, and is still further increased by 

 its movements of flexion and extension. In five or ten minutes it has 

 worked its way into the cell (Fig. 49, e-g). Its movements then slowly 

 cease, and it comes to rest near the nucleus, but sometimes a sporozoite 

 traverses four or five epithelial cells before settling down. 



Within the epithelial cell the sporozoite becomes a motionless 

 oval body, which absorbs the fatty nutriment provided for it by the 

 cell (see above, p. 208), without, however, forming any fat-granules 



