THE STRUCTURAL BASIS OP THE BODY 

 Their movements continued for a short tim 

 pulsations of the contractile vesicle were but 

 of digestion of food was completely lost 

 that Stentor, an infusorium whL 

 broken up into fragments of al. 

 one-twentv-seventh the volume of the 



Oth 



., 



2 





FIG. 9. Regeneration in the unicellular animal Stentur. (From GKUBKK after BALKIAM.) 

 A. Animal divided into three pieces, each containing a fragment of the nucleus. 

 B. The three fragments shortly afterwards. C. The three fragments after twenty-four 

 hours, each regenerated to a perfect animal. 



regeneration. The wound quickly heals and the special organs the mouth, 

 with its surrounding cilia, and the contractile vacuole are regenerated, but 

 all non-nucleated fragments quickly perish (Fig. 9). 



Many similar observations have shown that the non-nucleated cytoplasm, 

 though it may survive for some time and perform normal movements in 

 response to stimuli, such as those of ingestion of food particles, loses entirely 

 the power of digestion, secretion, and growth. In animals possessing a shell, 

 a small secretion of the lime salts may occur on the surface, but this process 

 rapidly comes to an end as the store of material in the cytoplasm is exhausted. 

 In vegetable cells it is possible to break up the protoplasm by means of 

 plasmolysis into nucleated and non-nucleated parts. The nucleated part 

 quickly forms a new cell wall. The non-nucleated part is unable to effect 

 this formation, and soon dies unless it is in connection with an adjacent 

 cell containing a nucleus by means of fine threads of protoplasm which 

 pass through pores in the intercellular septa (Fig. 10). In the higher animals 



