INDIVIDUATION AND REPRODUCTION 



233 



the development of buds can be induced, in spite of the presence and 

 activity of the chief growing tip, by subjecting the part concerned 

 to external conditions especially favorable for growth and develop- 

 ment. To what extent this process of physiological isolation occurs 

 in nature is as yet a question, though it probably occurs very fre- 

 quently. 



Many cases of agamic reproduction have not as yet been ana- 

 lyzed from this point of view, but it appears probable that all arc the 

 result of either physiological 

 or physical isolation. In 

 some cases, where the degree 

 of individuation is sHght, 

 physical isolation is probably 

 the primary factor, that is, 

 some internal or external con- 

 dition operates to isolate a 

 part physically from other 

 parts and reproduction re- 

 sults. This may occur in va- 

 rious cases of spore formation 

 among the lower plants, 

 although even here it is prob- 

 able that physical isolation is 

 possible only because the 

 parts are normally but 

 slightly subordinated to a 

 dominant region. 



We may conclude, then, 

 that the first step in agamic 

 reproduction is the isolation 



of a part from the correlative conditions in the individual which 

 determine its existence and persistence as a part. In at least 

 many cases this isolation is primarily physiological, rather than 

 physical. In consequence of tliis isolation the part undergoes 

 more or less dedifferentiation, a new individuation arises in it 

 in various ways, some of which have been analyzed in certain 

 cases (Child, '14/^ '14^), but which cannot be discussed here. 



Fig. ioi. — Longitudinal section of the 

 apical region of a seed plant: a, growing tip; 

 b, developing leaves; c, a.\illar>' buds. From 

 Strasburger, etc., '08. 



