THE PLAN OF PRESENT WORK 17 



such as chemistry, physics, and geology, and on the other with 

 the study of mankind and the works- of man. From morphology 

 and physiology we pass, though not without huge gaps in know- 

 ledge, to the study of mind (psychology), sociology, political 

 economy, law, ethics, and history, while even linguistic students 

 are nowadays confronted with problems best explained on an 

 evolutionary basis. 



THE PLAN OF PRESENT WORK 



Most popular modern books on zoology written in English 

 deal with the various groups seriatim, beginning with the highest 

 forms and ending with the less familiar creatures, our know- 

 ledge of which is mainly due to the microscope. Of such books 

 Cassell's Popular Natural History and Lydekker's Royal Natural 

 History may be mentioned as admirable types. 



This plan is not here followed, but an attempt is made to 

 treat the subject in a comparative manner, taking function as the 

 basis, and illustrating the various points as they occur by examples 

 taken from all or many of the animal groups. It is believed 

 that this plan is better adapted than the other for bringing into 

 relief the most interesting facts and theories of modern zoology. 

 Such a mode of treatment was once much in vogue, both in 

 lecture courses and in books like the late Dr. Carpenter's 

 Animal Physiology. 



A sketch of Classification will first be given, so as to familiarize 

 the reader with the chief groups of animals and the range in form 

 presented by the animal kingdom, especially as regards external 

 characters. Special attention will be given to familiar forms, 

 particularly such as are native, and those which may be com- 

 monly seen in zoological gardens. This will be followed by a 

 section on the Food and Feeding of Animals, with special refer- 

 ence to interesting modifications and adaptations resulting from 

 the various ways in which animals get their livelihood, if one may 

 use the expression. Animal Defences will next be treated, and 

 this section is closely connected with the preceding, as means 

 of defence are mainly necessary to protect animals from the 

 attempts of other animals to eat them. Breathing and Move- 

 ment, as two primary functions, will form the subject of the next 



two sections, under which will be fully treated adaptations for 

 VOL. I. 2 



