92 PROTOPLASM 



granules of the nucleus. I have already referred in an 

 earlier publication to the distribution of corresponding 

 granules in the protoplasm of the Bacteriacrc, CyanophyceaB, 

 diatoms, and certain thread algae. To the objects enumerated 

 before I can now add the beautiful diatom Surirella and the 

 alga Chantransia. 



Radiolaria 



In this group only the intracapsular protoplasm of the 

 large Thalassicolla nucleata was the object of investigation. 

 Since the material in stock derived from Naples was quite 

 unserviceable on account of its unsuitable preservation, I 

 could only investigate some old, and therefore not very thin, 

 sections of specimens which I had preserved myself in osmic 

 acid. As a matter of fact, I have hardly seen another object 

 which shows the meshed structure, more plainly than the 

 intracapsular protoplasm of this Eadiolarian. Fig. 2, a, on 

 Plate V., gives a picture of it which is in no way schematised, 

 but as true to nature as possible. The great resemblance, 

 in fact the really striking agreement, between this picture 

 -and the appearances presented by the artificial oil-lathers, is 

 astonishing. The nodal points of the framework stand out 

 very distinctly, and the radiate arrangement of the layer of 

 meshes bordering on the vacuoles or so-called albumen 

 spheres can everywhere be well seen. As is well known, 

 the intracapsular protoplasm of Thalassicolla contains 

 numerous large vacuoles or " albumen spheres " (R Hertwig), 

 some of which enclose concretions. In Fig. 2, &, Plate V., is 

 drawn a portion of a large vacuole of this kind, which con- 

 tains a concretion, while Fig. 2, a, represents the protoplasm of 

 one of the bridges between the large vacuoles. In the sections 

 investigated, the so-called albumen spheres showed no other 

 contents besides the concretions, and hence gave the impression 

 of ordinary large vacuoles. The width of the meshes of pro- 

 toplasm varies to some extent. Since a direct measurement 

 of such minute dimensions is somewhat difficult, I have 

 counted the number of meshes round one of the vacuoles 

 depicted on Fig. 2, a, and from the calculation of the circum- 

 ference of tlie vacuole I have fixed the breadth of the 



