An Outline of the History of Biology. n 



As regards the secondary or directive factors in evolu- 

 tion, attempts have been made to give statistical evi- 

 dence of the action of selection or elimination (Weldon, 

 Pearson); many detailed illustrations have been furnished 

 as to the utility or survival-value of trivial characters ; 

 the content of the phrase "struggle for existence" has 

 been enlarged; and the importance of various forms of 

 " Isolation" has been suggested (Romanes, Gulick). 



Great improvements in technical methods have made 

 analysis much more thorough. The microtome has 

 enabled us to dissect an animal in a new way in a con- 

 tinuous series of fine sections from which, if necessary, 

 an accurate model can be reconstructed. A young stu- 

 dent may now make better sections than was possible to 

 Huxley. Countless methods of rapid fixing and differ- 

 ential staining have greatly aided the investigation of 

 minute structure, and some attempt has even been made 

 to understand the chemistry of the changes. The 

 "method of Golgi" and its rivals have entirely altered 

 the aspect of neurology. The apochromatic lenses mark 

 an epoch in the evolution of the microscope. But a 

 volume would be needed to do justice to the influence of 

 methods on the progress of biology. 



This outline will become clearer if it be re-read after 

 the other chapters, but its drift may be shortly summed 

 up. The history of biology before Darwin 



, r J . i r- Summary. 



shows a progressive analysis of structure 

 and function; the progress of biology after Darwin shows 

 the increasingly penetrating influence of the evolution- 

 idea, the growth of a more critical and cautious scientific 

 spirit, a perfecting of methods of research, and tentative 

 suggestions towards the synthesis which must succeed 

 analysis. From different sides the minds of all are 

 turned towards the problem of constructing a working 

 thought-model of the organism in its individual develop- 

 ment, in its racial history, and in its everyday activities. 



