V GENERAL REFLECTIONS AND CONCLUSIONS 283 



Properly speaking, therefore, this factor of ' position ' belongs to 

 the second category of ' induction '. 



An ' induction' is simply an effect produced upon the parts 

 that are developing by other parts, or possibly by some factor in 

 the external environment. These inductions are, according to 

 Driesch, of the nature of those events which are brought about 

 by the addition of a single antecedent condition, an ( occasion ', 

 to an assemblage of antecedent conditions, as a spark fires 

 a rocket or the movement of a lever sets a piece of machinery 

 in operation ; or, in the language of physiology, the causes of 

 these inductions are stimuli, the effects, reactions or responses, 



FIG. 167. Diagram to illustrate Driesch's hypothesis of the part 

 played by the nucleus in development. A is the cytoplasm, T its toti- 

 potent nucleus, x v x 2 are stimuli. 



A is sensitive to x l and becomes A^ T is sensitive to A, and is set in 

 activity (To). A 1 being sensitive to Ta becomes A v and A l is sensitive to 

 # 2 , and so on. (After Driesch, 1894.) 



the quality and the quantity of which are determined not only by 

 the stimulus but also by the nature of the reacting body itself. 



The analysis of these ' inductions ' is not, however, yet complete. 

 Occurrences of this kind imply the stimulus, the reception of 

 the stimulus and the response. The first of these is some other 

 organ or some external agent ; the second and third are functions 

 of the organ which is to be produced ; and Driesch imagines 

 that while it is the cytoplasm which is receptive of the stimulus, 

 it is the nucleus which makes the response. Each totipotent 

 nucleus is supposed to contain ferment-like bodies; under the 

 influence of some stimulus received through the cytoplasm some 



