308. THE HISTORY AND SCOPE OF ZOOLOGY IX 



The old doctrine of types, wliicli was used by tlie 

 philosopliically-minded zoologists (and botanists) of 

 the first half of the century as a ready means of 

 explaining the failures and difficulties of the doctrine 

 of design, fell into its proper place under the new 

 dispensation. The adherence to type, the favourite 

 conception of the transcendental morphologist, was seen 

 to be nothing more than the expression of one of the 

 laws of Thremmatology, viz. the persistence of heredi- 

 tary transmission of ancestral characters, even when 

 they have ceased to be significant or valuable in the 

 struggle for existence : whilst the so-called evidences 

 of design wdiich was supposed to modify the limita- 

 tions of types assigned to himself by the Creator 

 were seen to be adaptations due to the selection and 

 intensification by selective breeding of fortuitous 

 congenital variations, which happened to prove more 

 useful than the many thousand other variations 

 which did not survive in the struggle for existence. 



Thus not only did Darwin's theory give a new 

 basis to the study of organic structure, but, whilst 

 rendering the general theory of organic evolution 

 equally acceptable and necessary, it explained the 

 existence of low and simple forms of life as survivals 

 of the earliest ancestry of more highly complex forms, 

 and revealed the classifications of the systematist as 

 unconscious attempts to construct the genealogical 

 tree or pedigree of plants and animals. Finally, it 

 brought the simplest living matter or formless proto- 

 plasm before the mental vision as the starting-point 

 whence, by the operation of necessary mechanical 



