vi ZOOLOGY FOR MEDICAL STUDENTS 



Physiology, and Pathology, with their clinical applications in the later 

 parts of the curriculum. 



III. To provide a reasonably up-to-date account of the more im- 

 portant animal parasites, more especially of the pathogenic microbes of 

 animal nature, and of the ways in which they are carried or harboured 

 by members of the animal kingdom other than man. 



Of these objects the last mentioned, though seeming at first sight to 

 be very important, is actually of far less importance than the first two ; 

 for specialized knowledge of the type indicated can readily be added 

 at a later stage, provided always that a sound foundation of general 

 zoological knowledge has been laid. Many teachers indeed favour its 

 relegation to a special course at a later stage of the medical curriculum. 

 The present writer is on the whole in favour of retaining it in the general 

 course in Zoology: (i) because the later parts of the curriculum are 

 already much complicated by the multiplicity of subjects, and tend to be- 

 come more and more so with increase of speciahzation ; (2) because various 

 parasitic forms of life are best studied along with their free-living allies ; 

 and (3) because many of the animal organisms that would naturally 

 come into such a specialized course can quite well be made use of in the 

 general course. 



The course represented by this book is preponderatingly morphological, 

 and this for two reasons. Firstly, because our knowledge of the morpho- 

 logical features of the lower types of animal is much more advanced than 

 our knowledge of their physiology. Secondly, because morphological 

 study affords an intellectual discipline better adapted to the needs of the 

 elementary student than that afforded by physiology. The student 

 observes structural features in the laboratory, and he records his observa- 

 tions in the form of drawings. He receives valuable training in observa- 

 tion and in the interpretation of observations ; and he is able to compare 

 what he observes with what he is told or reads. When, on the other 

 hand, he tries to make physiological observations he finds even in the 

 case of the simplest phenomena that behind these phenomena are at 

 work unseen powers and factors, unobservable and yet perhaps all- 

 important. He is taught that particular phenomena are due to metabol- 

 ism or to some obscure process of a physical or chemical character — but 

 these are, so far as he is concerned, transcendental, and as far beyond 

 his powers of comprehension or criticism as if they were the direct result 

 of supernatural agency. 



