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 

 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. 



