GENERAL CONSIDERATIONS. 853 



it is always observed that the organic nitrogenized constituents of the organism are 

 combined most intimately with a tolerably definite quantity of inorganic matter, which 

 latter regulates, to a certain extent, nutritive processes, and constitutes, also, an impor- 

 tant component part of the tissues. It is observed, in addition, that, during early life, 

 when the system is proceeding toward its perfect development by growth, the proportion 

 of inorganic matter is less than in the adult, and that the process of nutrition is then at 

 its maximum of activity, the regeneration being superior to the waste. During the adult 

 period, repair and physiological decay are nearly balanced ; but, in the decline of life, 

 there seems to be a gradual accumulation of inorganic matter, and this continues until 

 the so-called vital properties of some important organ become so feeble that its func- 

 tions cease, and we have physiological death. This regeneration of the tissues is a neces- 

 sary 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 conceive that living tissues exist 

 in an absolutely stationary condition. The organized parts of the body are undergoing 

 constant molecular destruction and repair. Again, the so-called vital properties of the 

 tissues, which involve self-regeneration, seem to have certain limits. We cannot intro- 

 duce nutritive matter in sufficient quantity to produce growth beyond a certain point, 

 although 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 nutritive 

 matter is presented, this excess is not used, we must confess our ignorance or say that 

 the parts are endowed with vital properties. We also find, to come to the most impor- 

 tant point of this discussion, that, however carefully we may supply nutritive matter to 

 the system, we cannot arrest the gradual 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 substance, so it is impossible for the organism to 

 last for an indefinite period. A necessary, invariable, and inevitable consequence of 

 individual life is death. The constant molecular death if we can apply this term to the 

 transformation of living into effete matter of every tissue of the body is always, in the 

 end, superior to the power of repair. There seems, indeed, to be an antagonism of pro- 

 cesses during life ; a view which was so fully adopted by Bichat, that it led to his cele- 

 brated definition of life ; " the ensemble of functions which resist death. 1 ' Although death 

 is thus inevitable, and, in the circulation of material in Nature, the organic parts of the 

 body become changed in the arrangement of their ultimate elements and appropriated by 

 the vegetable kingdom, during adult life, certain anatomical elements, male and female, are 

 formed in the human subject, which, when they come together under proper conditions, 

 develop into new beings, which pass through the same course of existence as the parents. 

 By the concourse of two beings, new organisms come into life, which perpetuate exist- 

 ence and preserve species. The function by which this is accomplished is called genera- 

 tion, or reproduction. 



In o"ur study of generation, we shall confine ourselves as closely as possible to the 

 process as it takes place in the human subject. There are many considerations of great 

 interest connected with the generation of the lowest orders of animal organization, 

 among the most prominent of which is the question of so-called spontaneous generation. 

 While this may have a certain bearing upon the genesis of anatomical elements, it has 

 little or nothing to do with the development of the fecundated human ovum, and will, 

 therefore, receive little more than an incidental consideration. For similar reasons, we 

 shall not engage in a discussion of the development-theory applied to the origin of spe- 

 cies, which is exciting so much controversy at the present day, nor shall we treat of gen- 

 eration in the lower animals, except to illustrate the history of development in man. 



