PHYSIOLOGY, CHEMISTRY AND MORPHOLOGY. 381 



selves. Now, from some of my studies, it seems to me that one may 

 conclude that stimulants to the nutritive activities for organic restora- 

 tion consist, in certain cases, at least, in the by-j)roducts, the scoriae, 

 the cinders that result from functional activity. 



These catabolic i)roducts gradually accumulate in the tissues and 

 pass from thence into the blood, which, continually circuhxting, trans- 

 ports them to the glands, by which they are again worked over and 

 tinally eliminated. It appears that it is precisely these by-products, 

 produced by our tissues when in activity, that give to nutritive phe- 

 nomena the impulse that excites to a renewal of the energy spent in 

 function, which leads the organ accomplishing a work to develop and 

 adapt itself to new demands of the individual and the environment. 

 In order to understand my assertion it must be remembered that the 

 tissues are never completely at rest ; that, on the contrary, as to mate- 

 rial matters they are constantly changing and are being ceaselessly, 

 though slowly, consumed; even when they show no internal evidence of 

 function. Yet the by-products occurring during this apparent func- 

 tional repose do not suflice to proj)erly maintain, or rather are not 

 suitable for setting up, this work of reconstruction, since an inactive 

 organ decreases, atrophies, and may be reduced to a rudimentary 

 state. When, on the contrary, it remains active, it maintains itself in 

 nutritive equilibrium, and increases in proportion to its greater or less 

 functional activity. This arises, at least in part, from the fact that 

 the by-products of the function ex(;ite to restorative work greater in 

 amount than the destruction that occurred during the period of activ- 

 ity, in fact, if an organ that only occasionally acts does not atrophy, 

 it is because that during its action it establishes such a stinuilation to 

 nutrition that it compensates not only for the losses occasioned by 

 activity, but also for those occurring during repose. Thus scientific 

 sanction is given to a fact of daily experience, viz: that an organ is 

 kept in good nutritive condition by a proper alternation of work and 

 rest. It is also seen why increased activity of the function of an organ 

 leads to its hypertrophy. Increase of work i^roduces, indeed, such an 

 amount of nutritive stimulation that, as a logical consequence of what 

 has been said, the losses that preceded the period of activity as well as 

 those which arise from it will not only be made good, but restored with 

 usury, and the organ will consequently be in a better nutritive condi- 

 tion than before. That is of course within physiological limits, for 

 excessive activity leads to tliose phenomena of auto-intoxication which 

 are collectively designated under the term fatigue. 



It is likewise certain that the chemical mechanism which I have now 

 brietly sketched out for you includes but one side of the question, and 

 that it is necessary to consider another which concerns itself with 

 moii)ho1ogical phenomena. The chemical elaborations by which tissues 

 dev«'l(>i> give rise to molecular i)olarizations, from which results the 

 structure <>f living beings. 



