12 ZOOLOGICAL PHILOSOPHY 



of recognised facts that nature, while ever increasing the complexity 

 of animal organisation, has created in order the different special organs, 

 as also the fimctions which the animals possess. 



The behef has long been held that there exists a sort of scale or 

 graduated chain among living bodies. Bonnet has developed this- 

 view ; but he did not prove it by facts derived from their organisa- 

 tion ; yet this was necessary especially with regard to animals. He 

 was unable to prove it, since at the time when he Uved the means did 

 not exist. 



In the study of all classes of animals there are many other things 

 to be seen besides the animal complexity. Among the subjects of 

 greatest importance in framing a rational philosophy are the effect 

 of the environment in the creation of new needs ; the effect of the needs 

 in giving rise to actions, and of repeated actions in creating habits, 

 and incUnations ; the results of increased or diminished use of any 

 organ, and the means adopted by nature to maintain and to perfect 

 all that has been acquired in organisation. 



But this study of animals, especially of the least perfect animals, 

 was long neglected ; since no suspicion existed of the great interest 

 which they exhibit. Moreover, what has been started in this respect 

 is still so new that we may anticipate much more light from its further 

 development. 



When the study of natural history was actually begun, and 

 naturalists inquired into both kingdoms, those who devoted their 

 researches to the animal kingdom studied chiefly the vertebrate animals, 

 that is to say mammals, birds, reptiles and, lastly, fishes. In these 

 classes of animals the species are in general larger, and have their 

 parts and functions better developed and more easily ascertainable 

 than the species of invertebrate animals. Their study, therefore, 

 seemed to present more of interest. 



In fact the majority of invertebrate animals are extremely small, 

 their functions are Umited, and their organs much more remote from 

 those of man than is the case of the more perfect animals. As a 

 result, they have been to some extent despised by the vulgar, and 

 down to our own time have only reahsed a very moderate amount 

 of interest on the part of most naturalists. 



We are beginning, however, to get over a prejudice so harmful to 

 the progress of knowledge. During the few years that these singular 

 animals have been closely examined, we have been compelled to 

 recognise that the study of them is highly interesting to the naturalist 

 and philosopher, because it sheds light, that could scarcely be other- 

 wise obtained, on a number of problems in natural history and animal 

 physics. It has been my duty in the Natural History Museum to 



