650 



WHITMAN. 



[Vol. VIII. 



eration are so exactly parallel that one cannot fail to see at 

 once that the formative forces operate in essentially the same 

 manner with the one-celled as with the many-celled organism. 

 Gruber's experiment, as described in his recent article, ''Micro- 

 scopic Vivisection'' {Berichte der Naturforschenden Gesellschaft 

 zu Freiburg, Vol. VII, Part i, 1893), illustrates well this point. 

 A Stentor was cut into three pieces, A, B, C, each of which 

 regenerated the missing parts within 24 hours. The anterior 



Fig. I. — Regeneration of a Stentor cut into three parts, A, B, C. j/c = pulsating 

 vacuole. S = regenerating frontal field. 



end regenerated posterior end, and vice versa. The middle 

 piece regenerated both ends — the complicated frontal field 

 with its mouth, pharynx, long cilia, pulsating vesicle, etc., as 

 well as the simpler posterior region. 



Treat a Hydra in the same way and similar results will follow. 

 In both cases the orientation of the parts will remain the same 

 as that of the whole. Gruber repeated the division of Stentor 

 four times in succession, getting perfect regeneration each 



