The study of animals is but a part of the wider science the study of organised matter generally the science of which takes plants as well as animals the objects of its investigations. Under the head biological studies we have therefore to group;  

(a) Those which regard organims as working machines capable of performing various functions these studies are physiological whether animals or plant be separately or simultaneously examined 

(b) The second place the parts which the organism is made up may be investigate and studies are then said be anatomical, we concern ourselves with isolated types as does the student of human anatomy; or they are morphological when we compare organisms and their parts one with another; and try to draw out the significance of isolated facts and to learn their bearing the general scheme of the organisation of living matter.. 

The present work is concerned only with animals but as there is a fundamental resemblance between Plants and Animal it is in the first place necessary to enquire into the characters and modes of activity ofliving matter, pure and simple without any question as to whether it be animal or vegetable..