ATROPHY OF INSTITUTIONS 281 



are absent and a single greatly enlarged cotyledon 

 is the sole assimilating organ. 1 



It is evident that in these oblique and horizontal 

 branches, the leaves directed vertically towards the 

 sky are in the most unfavourable position for assi- 

 milation, and that, in addition, their presence would 

 shade the leaves lying under them. In these 

 species the more or less complete reduction is an 

 inherited fixation of a sacrifice of these particular 

 leaves for the benefit of the whole organism. 



CHAPTEE II 



ATROPHY OF INSTITUTIONS 



THE causes of atrophy in institutions are more or 

 less analogous to those which bring about atrophy 

 of organs. First, there is atrophy from ivant of 

 use, when function either becomes useless or is 

 transferred to another institution. Atrophy from 

 lack of resources corresponds precisely with 

 atrophy from lack of nutrition. There is no- 

 thing, however, in the atrophy of institutions quite 

 analogous to that which, in organisms, results from 

 lack of space. But if the development of an 

 institution cannot be actually impeded by the co- 



1 See the figures of plants of this family in Fritsch, Gesneriacece. 

 (Engler und Prantl's naturlichen Pflanzenfamilien. Leipzig, 1891. ) 



