26 



GENERAL SKETCH OF THE CELL 



some respects that of Biitschli, protoplasm is compounded of innu- 

 merable minute granules which alone form its essential active basis ; 

 and while fibrillar or alveolar structures may occur, these are of only 

 secondary importance. 



Fig. 10. Alveolar or foam-structure of protoplasm, according to Biitschli. [BUTSCHLI.J 



A. Epidermal cell of the earthworm. B. Aster, attraction-sphere, and centrosome from sea- 

 urchin egg. C. Intracapsular protoplasm of a radiolarian ( Thalassicolla) with vacuoles. 

 D. Peripheral cytoplasm of sea-urchin egg. JE. Artificial emulsion of olive-oil, sodium chloride, 

 and water. 



It is impossible here adequately to review the many combinations 

 and modifications of these views which different investigators have 



