8 C. M. CHILD. 



parts of organisms in nature may occur in various ways: first, 

 increase in size beyond a certain limit may isolate physiologically 

 certain parts from the influence of a dominant part and so lead 

 to reproduction. Second, decrease in the metabolism of a 

 dominant part may decrease the effective distance of the correla- 

 tive factor and so lead to the physiological isolation of parts 

 without increase in size of the whole. Third, changes in the 

 character of the path of correlation may decrease the distance to 

 which conduction is possible and likewise bring about the 

 physiological isolation of parts. And finally, changes in the 

 receptiveness of subordinate parts may themselves isolate such 

 parts physiologically. 



In organisms where the parts in question are capable of regula- 

 tion such physiological isolation, however brought about, will 

 be followed by a regulatory reconstitution of the isolated part, 

 which may lead either to the formation of a new complete 

 individual, or a new part. The result of the physiological isola- 

 tion of a part depends upon its degree of differentiation and its 

 regulatory capacity as well as upon the. degree and kind of 

 physiological isolation. In my earlier paper examples of the 

 various types of physiological isolation were given and various 

 phenomena of asexual reproduction were analyzed in the light 

 of these ideas. 



In many cases the asexual reproductive element appears in a 

 more or less highly differentiated form, e. g., various forms of 

 spores, and in some cases it gives rise to something different from 

 that of which it originally formed a part, as for example in plants, 

 where the spore of the sporophyte gives rise to the gametophyte. 

 Such cases, however, do not in any way conflict with the general 

 conclusion that asexual reproduction is the result of physiological 

 or physical isolation of parts. 



If these conclusions are correct, asexual reproduction in nature 

 is essentially similar to the process of reproduction which occurs 

 when we isolate physically a piece of an organism. In the 

 natural process, however, the degree and kind of physiological 

 isolation and the localization of the part isolated are all deter- 

 mined by natural conditions, either internal or environmental. 



Moreover, the same considerations apply to the phenomena of 



