7<3 The Field Naturalist's Quarterly Feb. 



interest him more than the method on which those structures are built 

 up. In describing his discovery from this third point of view he is 

 describing the physiology of the animal, or the manner in which the 

 functions are performed during life. This is, again, an immense sub- 

 ject, and he will soon find that he is quite unable to account for all that 

 he sees. But he will soon perceive that all the functions which the 

 animal is capable of performing are one of three kinds. They are 

 either concerned with (a) Nutrition, (b) Reproduction, or if neither of 

 these, they are (c) directed to bringing the animal into relation with 

 the world around it. Every function is of one of these three kinds. 

 Breathing by gills, lungs, or the surface of the body is a matter of 

 keeping the body nourished, so are the various methods adopted by 

 animals to excrete waste products, so is the circulation of blood, so is 

 digestion. 



The special means adopted to reproduce offspring constitute the 

 reproductive functions, whether these be simply growing buds or more 

 complicated methods. Everything that is not either a nutritive or a 

 reproductive function belongs to the third group of functions, those 

 by which the animal comes into contact with its surroundings. Sight, 

 hearing, touch, smell, taste, consciousness, memory, thought, ideation, 

 and so forth, are all /unctions of relation. One cannot conceive of any 

 physiological function which is not directed to one of these three ends. 

 So that our naturalist has now described his animal from three distinct 

 aspects, and although that has involved much labour, it by no means 

 exhausts the matter. A further investigation may lead him to find out 

 that his new discovery, though now so rare, was at one period of the 

 world's history a much more common animal. There may be many 

 fossil examples of a similar creature. He must therefore describe its 

 distribution in Time, or its Palaeontology, as well as its distribution in 

 present space. The past and present distribution of the same forms of 

 life present some most interesting problems, and the two do not by any 

 means necessarily coincide. Thus he has completed a fourth aspect. 

 But then there is another. What is it that makes this animal different 

 from all others, and justifies its being regarded as a new form to 

 science? What characters has it which are peculiar to itself? Some 

 of its structures are common to many animals, but some there are 

 which no other animal possesses, and on account of these the discovery 

 is recognised as a new species. This is the aspect of specific characters. 

 Then there is an aspect which is really a combination of the morpho- 

 logical and the physiological, but which is such a large subject that 

 it is regarded as a separate aspect — namely, the study of the various 

 changes in form and function through which an organism passes before 

 it reaches the stage of maturity. This is the etnbryological aspect, or 

 the study of Embryology. Lastly, there is the philosophical aspect 

 of animal life, that which studies the connection of one kind of animal 

 with another, their relationships, their origin, their future, their asso- 

 ciation. This is the aspect of Evolution, which includes the study of 

 the most fascinating portion of biology, and is largely a theoretical 

 study as well as a practical one. It does not refer to an individual but 



