skins and dried plants. He is not content with numbering up so 

 many beasts, birds, and insects, as belonging to this or that district. 

 He looks to stracture in the lining animal or plant ; structure 

 in connection with the several functions it has to exercise. He 

 studies the gradual development of that stnicture from the merest 

 rudimentary combination of cell and membrane, or the protoplasm 

 preceding even that, till it assumes its perfect form. 



Take any one animal and trace its history from beginning to end. 

 Break the egg just dropped by the hen into its nest. Examine its 

 liquid contents, and judge of the work life has to do in building up 

 out of such materials what that egg is to give birth to. Mark that 

 small shining spot close upon the surface of the yolk-bag, where 

 life is to exhibit its amazing powers, its constructive skill. It is 

 the seat of a germ yet invisible to human eyes which within a few 

 days is to be developed into a feathered chick, in all respects like 

 its parent. What is it that will effect the marvellous transforma- 

 tion 1 Heat ; heat in conj unction with other physical forces, the 

 same forces that exert their influence over every part of the organic 

 and inorganic world alike, showing how all nature is held together 

 in one vast whole, subject everywhere to the same agencies, bound 

 by the same laws. 



Look again into the structure of the adult bird itself. Note its 

 framework of bones, its compacted muscles and sinews, its network 

 of arteries and veins by which the life-blood is conveyed to every 

 part, the organs that supply the whole with nourishment from 

 •without, above all the complicated nervous system leading up to 

 the brain, the seat of those faculties and instincts that enable the 

 creature to play its part in nature. And then, after a time, see these 

 functions and faculties waning and decaying, the structure becoming 

 more and more weak and powerless, and at length breaking down 

 under the influence of the same forces that had helped to build it 

 up, and given over to death. 



But life, considered in its outward manifestations, includes much 

 more than what I have referred to. This bird or other animal 

 does not stand alone upon the earth. It is surrounded on all sides 

 by hosts of other living creatures, some like itself, with the same 

 wants to supply, the same ends to attain ; others different, more or 



