May 28, 1897.] 



SCIENCE. 



819 



events determined from beginning to end by 

 the necessary response of cells and tissues, 

 in consequence of their inherent organiza- 

 tion, to the changed conditions. Given 

 the changed conditions on the one hand, 

 and the organization of the cells on 

 the other, the result must follow as surely 

 as night follows day, and this final result 

 influences the preceding series of events no 

 more in the one case than in the other. 

 That the cells possess the particular organi- 

 zation determining the manner of their re- 

 sponse to these changed conditions, and, 

 therefore, the beneficial character of the re- 

 sult, is dependent upon innate properties 

 whose fitness for the purpose doubtless has 

 been largely fixed by evolutionary factors, 

 operating, however, mainly in behalf of 

 physiological functions and not directly to- 

 ward pathological adjustments. In corre- 

 spondence with this view we find that our 

 knowledge of the manner of production of 

 the compensatory hypertrophies of various 

 organs and tissues stands in direct relation 

 to our knowledge of the physiology of the 

 same organs and tissues. 



Those compensatory hypertrophies into 

 the mechanism of whose production we have 

 the clearest insight are referable to increased 

 functional activity, and are, therefore, 

 spoken of as work-hj^pertrophies. This has 

 been proved for the muscular hj^pertrophies 

 and compensatory hj'pertrophy of the kid- 

 ney, but the demonstration is not equally 

 conclusive for the compensatory hj'pertro- 

 phy of other glands. I know, however, of 

 of no instance in which this factor in the 

 explanation can be positively excluded. 



The relationship between increased func- 

 tional activity and hypertrophy is so evident 

 in many cases that there is strong presump- 

 tion in favor of this explanation of those 

 glandular compensatory hypertrophies 

 ■which have not as yet been clearly referred 

 to the class of functional hypertrophies. 

 The very occurrence of compensatory hyper- 



trophy of an organ may direct attention to 

 the fact that it is endowed with definite 

 functions, and the conditions under which 

 the h j'pertrophy occurs may shed light upon 

 the nature of these functions. I need only 

 remind you of the significance, from this 

 point of view, of the compensatory hyper- 

 trophy of the thyroid, adrenal, pituitary, 

 and other glands with internal secretions. 

 I fail to see why Nothnagel should consider 

 a priori improbable the occurrence of com- 

 pensatory hypertrophy of one sexual gland 

 after loss of the other, even before sexual 

 maturity, or why Ribbert, who has appar- 

 ently demonstrated experimentally such an 

 occurrence, should find it necessary to seek 

 the explanation in reflex nervous influences 

 or mere byperfemia. The so-called second- 

 ary sexual characters and the changes fol- 

 lowing castration, including the influence 

 upon a hypertrophied prostate, point to im- 

 portant, even if little understood, functions 

 which for the present we can, perhaps, best 

 attribute to so-called internal secretions of 

 these sexual organs. 



The name compensatory hypertrophy is 

 sometimes applied to growths of tissue that 

 merely take the place of another kind of 

 tissue which has fallen out, as, for example, 

 the growth of adipose tissue around a 

 shrunken kidney or pancreas, or between 

 atrophied muscle-fibres. Here there is only 

 compensation of space, but no compensa- 

 tion of structure or function. Such hj'per- 

 trophies and growths are described better 

 as complementary than compensatory. 



Familiar examples of pathological hyper- 

 trophies from increased work are the hyper- 

 trophy of the heart from valvular disease 

 and other causes, that of the muscular coats 

 of canals and bladders behind some ob- 

 struction, and that of one kidney after loss 

 or atrophy of the other. 



In order to understand fully the manner 

 of production of work-hypertrophy of apart, 

 resulting from some morbid condition, it is 



