Regeneration 193 



that without any operation the apical ends of branches 

 which were in contact with soHd bodies continued to 

 grow as stolons, while those surrounded by sea water 

 continued to grow as stems. 



Herbst discovered a very interesting form of hetero- 

 morphosis in certain crustaceans; namely, that in the 



Fig. 36 



place of an eye which was cut off, an entirely different 

 organ could be formed, namely, an antenna. He 

 showed that the experimenter has it in his power to 

 determine whether the crustacean shall regenerate an 

 eye or an antenna in place of the eye. The latter will 

 take place when the optic ganglion is removed with the 

 eye, the former when it is not removed. These experi- 

 ments were carried out successfully on PalccmoUj 

 Palcemonetes, Sicyoniaj PalinuruSy and other crus- 

 taceans. 



The influence of gravitation is very famihar in plants; 



X3 



