322 HAND-BOOK OF PHYSIOLOGY. 



The mere acquirement of a certain shape by growth is not a pecu- 

 liarity of life. But the power of developing into so composite a mass even 

 as a vegetable cell is a property possessed by an organized being only. In 

 the increase of inorganic matter there is no development. The minutest 

 crystal of any given salt has exactly the same shape and intimate struc- 

 ture as the largest. With the growth there is no development. There is 

 increase of size with retention of the original shape, but nothing more. 

 And if we consider the matter a little we shall see a reason for this. In 

 all force-transformers, whether living or inorganic, with but few ex-, 

 ceptions and these are, probably, apparent only something more is 

 required than homogeneity of structure. There seems to be a need for 

 some mutual dependence of one part on another, some distinction of 

 qualities, which cannot happen when all portions are exactly alike. And 

 here lies the resemblance between a living being and an artificial machine. 

 Both are developments, and depend for their power of transforming force 

 on that mutual relation of the several parts of their structure which we 

 call organization. But here, also, lies a great difference. The develop- 

 ment of a living being is due to an inherent tendency to assume a certain 

 form; about which tendency we know absolutely nothing. We recognize 

 the fact, and that is all. The development of an inorganic machine 

 say an electrical apparatus is not due to any inherent or individual 

 property. It is the result of a power entirely from without; and we 

 know exactly how to construct it. 



Here, then, again, we recognize the compound nature of a living 

 being. In structure it is altogether different from a crystal in inherent 

 capacity of growth into definite shape it resembles it. Again, in the fact 

 of its organization it resembles. a machine made by man: in capacity of 

 growth it entirely differs from it. In regard, therefore, to structure, 

 growth, and development, it has combined in itself qualities which in all 

 other things are more or less completely separated. 



That modification of ordinary growth and development called gener- 

 ation, which consists in the natural production and separation of a portion 

 of organized structure, with power itself to transform force so as there- 

 with to build up an organism like the being from which it was thrown 

 off, is another distinctive peculiarity of a living being. We know of 

 nothing like it in the inorganic world. And the distinction is the greater 

 because it is the fulfilment of a purpose, toward which life is evidently, 

 from its very beginning, constantly tending. It is as natural a destiny 

 to separate parts which shall form independent beings as it is to develop 

 a limb. Hence it is another instance of that carrying out of certain pro- 

 jects, from the very beginning in view, which is so characteristic of things 

 living and of no other. 



It is especially in the discharge of what are called the animal func- 

 tions that we see vital force most strangely manifested. It is true that 



