BLOOD CORPUSCLES OF THE FROG 127 



radiate mesh work of the large portion of this region. That 

 this radiate protoplasm is really composed of a reticulate 

 meshwork can be demonstrated quite plainly. The proto- 

 plasm of the central area passes again immediately into 

 the more strongly stained radiating external protoplasm. 

 In this section the radiate arrangement of the external 

 protoplasm was less strongly pronounced than is the case as 

 a rule, but was nevertheless to be seen clearly in many 

 places. As I have already pointed out above, the stronger 

 tingibility of the external protoplasm certainly depends on 

 the numerous strongly staining granules which are lodged 

 in it, and not on an alteration in the nature of the real 

 framework. In order to show this fact quite plainly in the 

 figure, the section should, of course, have possessed the thick- 

 ness of only a single layer of meshes. But these sections 

 were not so thin (about 0'002 mm.), for which reason the 

 external mass of protoplasm still shows an apparently diffuse 

 staining. 



Sections through the ovarian eggs of Barbus fluviatilis 

 preserved in Mliller's Fluid, especially those through larger 

 eggs, show the fine meshwork most distinctly, as also a 

 well-developed radially striated layer of marginal alveoli, 

 1 fju in thickness, under the egg membrane. In the largest 

 eggs the radiate markings reach about four or five times 

 deeper, which permits the supposition that we are con- 

 fronted here by conditions similar to those obtaining in the 

 peripheral zone of the protoplasm of the central capsule 

 of Thalassicolla. Eadiately striated protoplasm frequently 

 occurred also round the germinal vesicle of the larger ova, 

 which could be seen to owe its arrangement to a special 

 arrangement of the meshes. The meshed structure of the 

 protoplasm and the marginal alveolar layer could also be 

 recognised in the ovarian eggs of Dreissensia polymorpha, 

 on examination of some older sections, though not quite 

 so plainly as in the eggs first mentioned. 



5. Red Blood Corpiiscles of JRana esculenta 

 On the occasion of some investigations upon the struc- 



