824 



SCIENCE. 



[N. S. Vol. V. No. 126. 



hypertrophied heart is at no disadvantage 

 in this respect. As pointed out with es- 

 pecial clearness by Martius, the significance 

 of this alteration in the ratio normally ex- 

 isting between the energy expended for 

 ordinary needs and that available for un- 

 usual demands is that it furnishes an ex- 

 planation of the greater liability of the 

 hypertrophied heart to tire upon exertion. 

 Fatigue of the heart is manifested by dilata- 

 tion of its cavities, and when this dilatation 

 from fatigue is added to that already exist- 

 ing in most cases, relative insufficiency of 

 the mitral or tricuspid valve is likely to 

 occur, and the compensation is, at least for 

 a time, disturbed. The circulation through 

 the coronary arteries, whose integrity is so 

 important for the welfare of the heart, is 

 impaired, and a vicious circle may be estab- 

 lished. Notwithstanding the valuable con- 

 tributions from the Leipzig clinic as to the 

 frequency of various anatomical lesions in 

 the muscles of hypertrophied hearts, it does 

 not seem to me necessary to have recourse 

 to them as an indispensable factor in the 

 explanation of the breakage of compensa- 

 tion ; but I shall not here enter into a dis- 

 cussion of the general subject of the causes 

 of failure of compensation. 



I have described, with some detail, al- 

 though very inadequately, the manner of 

 production of compensatory hypertrophy of 

 the heart, in order, by this representative 

 example, to make clear what seem to me to 

 be certain general characteristics of many 

 adaptive pathological processes, and I beg 

 here to call attention especially to the follow- 

 ing points. As has been emphasized by 

 Nothnagel and others, no teleological idea 

 or form of language need enter into the ex- 

 planation of the mechanism of the process. 

 The final result is the necessary consequence 

 of the underlying morbid conditions. We 

 have satisfactory mechanical explanations 

 for essential steps in the process, and there 

 is no reason to assume that other than me- 



chanical factors are concerned in those vital 

 manifestations which at present we are un- 

 able to explain by known physical and 

 chemical forces. The properties of the cells 

 which determine the character of their re- 

 sponse to the changed conditions are none 

 other than their well-known physiological 

 properties. The adaptation finally secured, 

 admirable as it is in many respects, and 

 perhaps adequate for a long and active life, 

 is generally attended with marked imper- 

 fections, and, strictly speaking, is not a com- 

 plete compensation. It does not present 

 that coordinate and special fitness which we 

 are accustomed to find in physiological 

 adaptations, for the explanation of which so 

 much has been gained by the study of the 

 factors concerned in organic evolution. 



It may be argued that under the circum- 

 stances no better kind or degree of adapta- 

 tion can be conceived of than that which 

 actually occurs, and that the operation of 

 evolutionary factors, with special reference 

 to the adjustment of the organism to the 

 conditions causing cardiac hypertrophy, 

 could not secure any better result. I think 

 that it is not difficult to conceive how im- 

 provements might be introduced. It is, 

 however, permissible to suppose that the 

 introduction into the workings of the 

 organism of some better mechanism to com- 

 pensate the morbid conditions might be at 

 the sacrifice of more important physiolog- 

 ical attributes of the body. More perfect 

 pathological adaptations might in many 

 instances involve a deterioration of the 

 physiological characters of the species. It 

 is often the case that the more highly or- 

 ganized living beings lack some capacity 

 possessed by those lower in the scale of 

 organization to resist or compensate injury 

 and disease. This is notably true of the 

 power to regenerate lost parts. It is, how- 

 ever, along the lines of improvement in the 

 physiological characters of the individual 

 or species that the opportunity often lies 



