THE FACTORS OF ATROPHY 



253 



species, is the result of a struggle amongst the 



organs produced by a scanty water supply. The 



leaves attract to themselves the greater part of 



the water absorbed by the roots, 



and thus retard the growth of 



the stem. But if the plant be 



cultivated in an atmosphere satur- 



ated with water, the struggle be- 



tween the leaves and stem is 



stopped, and the stem grows to 



a much greater extent (fig. 73, 



B, p. 236). 



View, Faba, like most vetches, 

 produces at germination rudi- 

 mentary leaves, and similar leaves 

 are borne at the base of each 

 branch. Goebel has shown that 

 these rudimentary leaves may be 

 made to grow by cutting away 

 the terminal buds at a young 

 stage. In this way the struggle 

 between the first formed and later 

 leaves is suppressed. 



In the case of the individual, 

 atrophy results from the struggle 

 for existence amongst the organs. 

 In atrophy throughout a species it is the struggle 

 for existence amongst individuals that plays the 

 chief part. Clearly in this struggle, useless organs 

 become impediments and burdens. If any organs 



FIG. 75. Two seedlings 

 of deer arietinum. 



darkness - 



