[33] 



Zbc flDammalia: 

 leytinct Species an& Surviving jforma. 



By Mrs. Alice Bodington. 

 Plates v., VI., VII. 



THE lovers of Zoology find their favourite study become ever 

 increasingly fascinating, as the discoveries of modern 

 palaeontology more and more triumphantly vindicnte the 

 theory of evolution. Although that theory received its greatest 

 impetus in England and on the Continent from the works of 

 Darwin, yet it is evident that the great master himself had only 

 grasped one form of the law governing evolution. He sought, 

 at least in his earlier works, to account for all changes in 

 animals and plants by natural selection ; whereas we now see that 

 the infinite, delicate variations in the world of organic beings are 

 owing to the intense irritability and susceptibility to molecular 

 changes of protoplasm, and the consequent action of the environ- 

 ment upon it. Natural selection evoked some unknown force 

 vaguely of the nature of will. The action of the environment 

 upon protoplasm requires nothing but ordinary and well-known 

 phenomena of organic chemistry. 



In 1861, Darwin thought the " direct action of the conditions 

 of life cannot but have played an extremely small part in produc- 

 ing all the numerous and beautiful variations in every living 

 creature." But in one of his later letters we see how much he 

 had seen reason to change his views on this point, for he says : — 

 *' In my opinion, the greatest error I have committed has been in 

 not allowing sufficient weight to the direct action of the environ- 

 ment, independently of natural selection." Natural selection is 

 by no means excluded, but plays only a subordinate part in the 

 great drama of development. 



The zoologist can now trace pedigrees to which the longest 

 human pedigree is but as the flash of a second ; a pedigree show- 

 ing the most delicate and gradual changes : a cusp of a tooth 

 disappearing here, a joint becoming anchylosed there, yet by 

 slight, constant variations affecting the most startling changes of 

 structure. He can trace the camel, the horse, the dog, the cat, to 



Journal OF Microscopy and Natural Science. 



New Series. Vol. II. 1889. e 



