216 



PROCEEDINGS OF THE ACADEMY OF 



[Mar., 



staining cytoplasm of the remainder of the spore. Thus, when 

 viewed with powers of only 200 to 300, the spores show two very 

 clear-cut oval areas, the nucleus in the posterior half and the differ- 

 entiated area in front, and this latter is sometimes so faintly stained 

 that the complete outline of the spore cannot be followed. 



The clear region is sometimes oval, sometimes truncated behind, 

 as shown in the figure. It may be spoken of "as the rostrum of the 

 spore. Behind it, the cytoplasm abruptly assumes the character 

 which it possesses in the remaining portion of the spore where it is 

 densely staining and conspicuously alveolar. It is to be noted, how- 



Spores of Sarcocystis leporum. X 3500. 



ever, that the cytoplasm nearest the rostrum shows the coarsest 

 alveoli, while backward the alveoli become smaller and smaller, so 

 that in many cases the cytoplasm in the posterior half of the spore 

 becomes very dense, on account of the excessive minuteness of the 

 alveoli. In other cases, however, the alveoli are distinctly visible 

 throughout the entire extent of the dense spongioplasm of the cell. 

 At times, also, the spongioplasm encroaches somewhat upon the 

 homogeneous cytoplasm of the rostrum, there being here visible 

 one or more alveoli or one or more strands of spongioplasm. There 

 is, finally, often to be seen one or two clearer regions in the cytoplasm 

 between the rostrum and nucleus, but it is not believed that these 

 represent morphological entities. 



Following the rule for the spores of Sarcosporidia, there is no mem- 

 brane, the spores being naked masses of protoplasm. 



The nucleus may occupy nearly any position in the cell, but it is 

 usually placed near the posterior end. Although, as already stated, 



