Regeneration as Fii7ictional Adjustment 42 1 



diagram in which the differentiated cells are represented bv the 

 larger circles A, B, C, etc., and the indifferent cells by the smaller 

 circles between them. Each cell such as A contributes something 

 utilized by B, G and F, and derives something in return from each 

 of these sources. Now suppose A is removed; the indifferent cell 

 lying near by,. no longer held in check by the same stimuli, begins 

 to grow and develop. What line of differentiation will it most 

 naturally take. Owing to the symbiotic relation subsisting be- 

 tween the cells differentiation in the direction of A will be most 

 favored as this secures it the advantages which A received. In 

 other words, this will be the direction of development alongwhich 

 social pressure will tend to guide it. And the result will be a re- 



©:®:® 



Fig. I 



generation of the missing part." For applications of this theory 

 here set forth in barest outline to morphallaxis, heteromorphosis, 

 physiological regeneration, and other modes of regulation, refer- 

 ence may be made to my former paper. 



In some recent articles the problem of regulation has been ap- 

 proached from points of view somewhat similar to my own. Jen- 

 nings- has attempted to show that regulation in behavior is funda- 

 mentally similar to other forms of regulation. The method of 

 trial and error, which is so pronounced a feature of the behavior 

 of lower organisms, and one through which they secure a large 

 part of their adaptations to external conditions, is assumed by 

 Jennings to be followed in the various processes occurring in 



^ This Journal, vol. ii, and Behavior of the Lower Organisms. New York, i<;o6. 



