THE CYTOPLASM 



43 



" microsomes " in sections of actual protoplasm. After impregnating 

 pith with peptone-solution and then hardening, sectioning, and stain- 

 ing, the cells may even contain a central nucleus-like mass suspended 

 in a network of anastomosing threads that extend in every direction 

 outward to the walls, and give a remarkable likeness of a normal cell. 

 These facts show how cautious we must be in judging the appear- 

 ances seen in preserved cells, and justify in some measure the hesita- 





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ftsnwuiiMtinniaiuunuiKr 



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CD 



Fig. 17. — Ciliated cells, showing cytoplasmic fibrillae terminating in a zone of peripheral 

 microsomes to which the cilia are attached. [EngelmaNN.] 



A. From intestinal epithelium of Anodonta. B. From gill of Anodonta. CD. Intestinal epi- 

 thelium of Cyclas. 



tion with which many existing accounts of cell-structure are received. 

 The evidence is nevertheless overwhelmingly strong, as I believe, 

 that not only the fibrillar and alveolar formations, but also the micro- 

 somes observed in cell-structures, are in part normal structures. This 

 evidence is derived partly from a study of the living cell, partly from 

 the regular and characteristic arrangement of the thread-work and 



