CAN ORGANS RESUME THEIR PRIMITIVE FUNCTIONS? 233 



The only cases show that in them no great amount 

 of degeneration had taken place. 



1. Muscles of the ear in man. It is known that 

 the human ear possesses a number of intrinsic and 

 extrinsic muscles reduced to delicate fibres, and 

 incapable of producing movement of the whole ear 

 or of one part of the ear on another part. In some 

 abnormal persons, however, certain of these muscles 

 may be well developed, making movements of the 

 ear possible. 



2. The abdomen and appendages in deep-sea 

 hermit-crabs. The hermit-crabs of the deep sea are 

 another instance of reversion to an ancestral form. 

 Littoral hermit-crabs inhabit the spiral shells of 

 Gastropods, and to suit this mode of life the body is 

 unsymmetrical, the appendages of one side being 

 rudimentary. In the depths of the ocean such 

 spiral shells are rare, and the crabs either abandon 

 this mode of life or live in straighter shells. In 

 consequence the limbs and the abdomen become 

 nearly symmetrical again. It is plain, however, that 

 in the littoral crabs these structures are not truly 

 rudimentary. 



II. Plants. In plants it is very difficult to 

 distinguish between the reappearance of lost organs 

 and the formation of new organs. 



1. Hermaphrodite flowers in Melandryum. The 

 Hermaphrodite flowers of melandryum (fig. 59) may 

 be flowers which after being unisexual have again 

 become hermaphrodite, or they may have retained 



