INTRODUCTION. IX 



of practical facts from abstruse theories. The cul- 

 tivation of fruits and the sale of flowers, by giving 

 a profitable occupation to thousands of persons, have 

 popularised the study of botany, that elder sister of 

 the other natural sciences which perhaps owes its 

 first popularity to its early association with medicine : 

 while mineralogy and geology, after having been 

 long studied in consideration of the light which they 

 might throw upon the practical working of mines, 

 have of late been also applied to agriculture. 



It is only within the last few years that zoology 

 has been directly applied to any objects capable of 

 yielding a profitable return. The light which this 

 science was able to throw on the phenomena of life 

 was not sufficient to attach to it the attention of the 

 general public, who number among their body men 

 of distinguished eminence in special departments, but 

 who too often do not esteem any science but the one 

 to which they are exclusively devoted. Many of 

 our most distinguished savants are often as blind as 

 the most illiterate of their fellow-citizens to the direct 

 applications of any department of knowledge of 

 which they are themselves ignorant. Thus, for ex- 

 ample, they cannot comprehend that the breeding of 

 agricultural stock and the cultivation of domestic 

 animals two most important problems regarding 

 which our knowledge has hitherto been merely 

 empirical are only definitely based upon the science 

 of zoology. 



