THE FACTORS OF ATROPHY 257 



An institution which has become useless and 

 burdensome is generally suppressed before its- 

 complete degenerative evolution is accomplished. 

 This suppression may be either voluntary as in 

 the liquidation of a commercial company, for 

 instance or it may be enforced. By the terms 

 of Article 73 of the Belgian Company's Act, 

 " the dissolution must be declared upon the 

 demand of all those interested at the termina- 

 tion of six months from the time when the 

 number of shareholders has been reduced to less 

 than seven." 



The downfall is generally effected in this sudden 

 way, either voluntarily by the interested parties, or 

 by the intervention of legislative means. 1 



Sometimes, however, artificial selection does occur, 



1 The occurrence of autotomy or self-mutilation in animals, as 

 in crabs, has analogies with what we have been discussing. 

 Similarly some plants brought into a new locality suddenly 

 shed their leaves. Ranunculus aquatilis, cultivated in water, 

 produces long divided leaves without stornata and with chloro- 

 phyll in the epidermic cells. If, from some chance, the water 

 falls below the level of the plants, the adult leaves become dry 

 and perish. The very young leaves growing unsubmerged are 

 still divided, but to a lesser extent ; they have stomata, and the 

 epidermis is devoid of chlorophyll. If the plants be again sub- 

 merged, this form of leaf dies, and there is a new development 

 from the youngest leaves of the normal aquatic type. 



Other plants show similar occurrences. Thus, when a Fuchsia 

 that has been cultivated in a conservatory is exposed to the air, 

 all its leaves are shed and are replaced by new leaves. These new 

 leaves again fall at once if the plant be brought back into the 

 conservatory. This is a real case of autotomy in plants. 



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