28o 



The Museum Gazette 



elapsed. In facetious allusion to doctrines on this head, 

 our contemporary, Punch, suggested that a man wishing to 

 acquire wings should stand on his house-top and wave his 

 arms about until the feathers grew, adding, " But it requires 

 much patience." The conversion of a swamp-loving pig into 

 a sea-going whale is almost equally incredible of attainment, 

 but it has been accomplished. We cannot doubt that it has 

 required great patience. It is a most important feature in 

 these marvellous transformations that they have occurred, 

 not in single instances, but in many, and in representatives of 

 different classes of animals. 



In the development of the embryo from the egg, much is 

 at first provided which will not in the end be wanted. The 

 subsequent stages are those of suppression of many struc- 

 tures and free growth of others. The suppression is, however, 

 often incomplete and the original rudiment, which failed to 

 grow, may be still recognised in adult life. Thus males have 

 nipples although their breasts as active glands have been 

 almost wholly suppressed ; and the narwhal, which has only 

 the tooth, or tusk, of one side of its upper jaw developed, has 

 the rudimentary tooth of the other side concealed in its socket. 

 Some animals which are hairless when grown up have hair 

 before birth, e.g., Sirenia, whales, &c. Some which are in 

 their youth toothless are not so in their yet earlier stages. 

 This tendency to suppression of certain structures may often 

 be explained in part or wholly by the demands for over- 

 growth made by some competitor (as in the instance of 

 the narwhal's tusk). This, however, does not explain the 

 whole, for sometimes the suppression occurs without any 

 competition. Thus in albinos there is a failure of the 

 pigment-producing structures, and in some instances this 

 involves the hair and skin-glands as well. 



No branch of science, or department of knowledge, can 

 afford to neglect the history of its own development. The 



