210 SCIENTIFIC THOUGHT. 



spectroscope), into the still wider conception of a general 

 science of evolution, as enunciated already forty years 



11. ago in the writings of Herbert Spencer, and in a more 

 spencer. shadowy form by Herder in the eighteenth century, and 



by Leibniz in the seventeenth. 



Seeing, then, that the treatment of the descriptive 

 sciences of nature has been so radically changed during 

 the course of the century, and that the change has been 

 accompanied by a complete revolution in our modes of 

 thinking and reasoning on these subjects, the historian of 

 Thought cannot be content with merely chronicling the 

 progress of the methods in use in the separate sciences, 

 such as mineralogy, geology, botany, and zoology, even 

 with the addition of the more recent sciences of palae- 

 ontology, physiology, and comparative anatomy. He 

 might in doing so fairly grasp the history of the descrip- 

 tive sciences up to the year 1850. It is exactly in this 



12. manner that Whewell, in his ' History of the Inductive 

 divisions Sciences,' treated this part of his subject. Beyond that 



abandoned. 



period the old landmarks designated by those names 

 have disappeared or become of secondary importance. 

 On the other side, whilst a history of Evolution in 

 Science might seize on the great characteristic feature 

 of the more modern research which belongs to the 

 second half of the century, it would hardly suffice to 

 sum up the leading ideas of the descriptive branches 

 of science as they were carried on on independent 

 lines during the earlier years of our period. Evolu- 

 tion had then no definite meaning, and Biology was 

 a disregarded term. We must thus look out for some 

 more general aspects which belong alike to the earlier 



