THE WOMBAT. 



The principle of evolution is now so thoroughly established 

 that no one doubts its correctness, especially since natural 

 history has thrown off such a number of branches — em- 

 bryology, bacteriology, paleontology, etc. — all of which send 

 a flood of light regarding the ground substance of which all 

 living organisms are built. The time has long passed when 

 it would have caused any surprise to remark that all organisms 

 are built of much the same substance, whether the tiny 

 zoophyte of the ocean bottom, or the largest of plant 

 structures, or man himself. The relationship between man 

 and the lower animals is clearly shown by many everyday 

 facts. Apart altogether from our physical structure there are 

 many points to consider. For instance, we can appropriate 

 parts of them without the intermediate processes of digestion 

 and assimilation ; this is so when we take a piece of skin or 

 bone from one of the lower animals and transplant it, when it 

 will grow and eventually become part and parcel of the living 

 man. In cases of myxcedema, a somewhat common disease, 

 the treatment adopted is a splendid example of what I want 

 to explain. It consists of supplying the affected persons with 

 the thyroids of other animals, chiefly sheep. A part of the 

 sheep's thyroid is planted under the skin of the diseased 

 person, and this part grows and eventually performs the 

 duties and functions of the diseased organ. Thus the course 

 of the disease is stopped, and the affected person invariably 

 recovers. Much more evidence could be cited, but I have 

 said enough to show you that natural science teaches us to 

 recognise the relationship in the substance of which all living 

 things are composed. 



* Protoplasm forms the simplest and least complicated 

 forms of living things, and simply becomes differentiated in 

 the course of growth and development. Simple, un- 

 differentiated protoplasm has a fairly definite chemical com- 

 position, consisting chiefly of albumen ; it is supposed that 

 albumen has a thousand atoms in each of its molecules, and 

 protoplasm probably many hundred times as many. 



There is, you must remember, a relation between living 

 matter and what may be conveniently called dead matter, i.e., 

 matter which is not living. We see how living matter takes 

 up dead materials and converts them to its own use, at the 

 same time giving off parts of itself in return. These are 

 mostly processes of oxidation, and constitute the main basis 

 of all life — physical and mental. Such a process continually 

 goes on under the name of respiration, by which the protoplasm 

 is being broken up ; digestion and assimilation are processes 

 by which it is being continually renewed. If the latter 

 process goes on faster than the former, the body grows. The 

 two processes never completely balance. After a time waste 



* See Dr. Cherry's " Beginnings of Life." 



