1016 CHARACTERISTICS OF DIFFERENT AGES. 



the one which seems to bear most directly upon the formative operations) ; 

 these forces being metamorphosed, so to speak, into the constructive force of 

 the living body, in virtue of the peculiar endowments of its material sub- 

 stratum, just as an Electric current transmitted through the different nerves 

 of Sense, produces the sensory impressions which are characteristic of each 

 respectively ( 592) ; or as the same current, transmitted through one form 

 of Inorganic matter, produces Light and Heat, through another, Chemical 

 Change, or through another, Magnetism. But we must also recognize in the 

 Organism at large, as well as in every integral part of it ( 330), a certain 

 capacity for growth and development which is the original endowment of 

 its germ which not only determines the mode in which it shall progressively 

 evolve itself into the fabric characteristic of its species and sex, but also 

 shapes the peculiarities of the individual, which serves also to bring about 

 the perpetual reconstruction that is needed for its continued maintenance, 

 and is peculiarly manifested in those reparative processes which make good 

 losses of its substance resulting from injury or disease, and of which the 

 cessation, by preventing any further metamorphosis of Physical into Vital 

 force, causes the constructive powers to fail altogether, so that the Organism 

 is resolved back by these very forces into the various forms of Inorganic 

 matter at the expense of which it had been built up. 



862. Now this "germinal capacity " is most strikingly displayed during 

 those earliest periods of existence, in which growth and development alike 

 are taking place most rapidly; in fact, the further we go back in the history 

 of intrauterine life, the more energetic do we perceive its manifestations to 

 be. For when we look simply at the increase from the minute point that 

 constitutes the first perceptible germ, to the mature foetus of 6 or 7 pounds 

 weight, we see that at no other period of existence can that increase be com- 

 pared in its rate, with that which presents itself during the nine months 

 that follow conception ; and if we go more into detail, we find that it is yet 

 more remarkable iu the earlier than in the later months ( 864). So, again, 

 it is in the first few weeks of embryonic life, that the foundation is laid of 

 most of its permanent organs, in the midst of an apparently homogeneous 

 mass of cells; whilst in the succeeding weeks, these rudiments are evolved 

 into the semblance of the forms they are subsequently to present, and a dif- 

 ferentiation of tissues begins to show itself in their several parts ; so that 

 the developmental process is so far advanced at little more than half the 

 term of gestation, that the foetus may even then, under favorable circum- 

 stances, maintain an independent existence ( 764). The rate of increase 

 becomes progressively slower during the advance from infancy to maturity; 

 and the energy of the developmental process is comparatively enfeebled, 

 being limited to the perfecting of structures whose foundations had been 

 previously laid, and in no instance manifesting itself normally in the evolu- 

 tion of a new part or organ. Now as there is no limit (in the well-nourished 

 individual) to the supply of Food and Warmth, it follows that this gradual 

 decline of formative activity must be due to a diminution of the capacity for 

 that activity, inherent in the organism itself; and this diminution is still 

 more strongly marked by that entire cessation, both of increase, and of 

 further developmental changes, which constitutes the termination of the 

 first period. For the organism which has attained that stage of its exist- 

 ence, has so far lost the formative capacity which characterized its earlier 

 years, that, however copious the supply of food, however abundant the gen- 

 eration of heat, it can thenceforth do no more than maintain its normal 

 condition, and can effect this for only a limited term of years. It seems a 

 necessary sequence of this series of phenomena, that the time should come, 

 when, after a period of gradual decliue, the germinal capacity of the organ- 



