EXHAUSTIVE NESS. 63 



could rather than publish many miscellaneous 

 and imperfect observations." Orchids furnished 

 an extreme case ; and his work on them is fas- 

 cinating from the nature of the subject, the end 

 aimed at, and the ingenuity of the reasoning 

 employed. He showed "how admirably these 

 plants are constructed so as to permit of, or to 

 favor, or to necessitate cross-fertilization " ; but 

 the way in which he did it is as admirable from 

 a logical point of view as the flowers them- 

 selves are in their peculiar adaptation. By 

 thus selecting judiciously the most extreme 

 special cases for exhaustive examination, he 

 threw the strongest light on all the collateral 

 evidence, and made it easy for him to under 

 stand its significance. On the shoulders of 

 such work his theories sat firmly, and it made 

 it easy for those who came after him to work 

 out the classes of facts which he was not able 

 to exhaust. 



In each of the many special studies which he 

 carried on there are many models of method in 

 the pursuit of details. The following case is 

 especially interesting because it illustrates both 

 the habitual care of the authors in their experi- 

 ments on the movements of plants and the ex- 

 treme liability to error that results from a 

 wrong start. Since the book on the " Power of 



