256 GENERATION. 



proportion of inorganic matter is less than in the adult, and 

 that the process of nutrition is then at its maximum of activ- 

 ity, the regeneration being superior to the waste. During the 

 adult period, repair and physiological decay are nearly bal- 

 anced ; but, in the decline of life, there seems to be a grad- 

 ual accumulation of inorganic matter, and this continues un- 

 til the so-called vital properties of some important organ be- 

 come so feeble that its functions cease, and we have physio- 

 logical death. This regeneration of the tissues is a necessary 

 consequence of the constant waste or decay of every part of 

 the organism, resulting in a change of constituents into effete 

 matters, which are discharged ; there being, during life, a 

 constant waste and repair. If no new matter be introduced 

 as food, the system wastes to a point which is incompatible 

 with life, and death results from inanition. 



With some very insignificant exceptions, we cannot con- 

 ceive that living tissues exist in an absolutely stationary con- 

 dition. The organized parts of the body are undergoing con- 

 stant molecular destruction and repair. Again, the so-called 

 vital properties of the tissues, which involve self-regenera- 

 tion, seem to have certain limits. We cannot introduce nutri- 

 tive matter in sufficient quantity to produce growth beyond a 

 certain point, though we may limit development and growth 

 by deficient supply. When we ask why the organs develop 

 with fixed regularity, why, when an occasional excess of nutri- 

 tive matter is presented, this excess is not used, we must con- 

 fess our ignorance, or say that the parts are endowed with vi- 

 tal properties. We also find, to come to the most important 

 point of this discussion, that, however carefully we may sup- 

 ply nutritive matter to the system, we cannot arrest the grad- 

 ual enfeeblement of the assimilative powers of the tissues, 

 which occurs in old age. In short, as we cannot conceive of 

 a living tissue without decay and regeneration of its sub- 

 stance, so it is impossible for the organism to last for an in- 

 definite period. A necessary, invariable, and inevitable con- 

 sequence of individual life is death. The constant molecular 



