542 OLD AGE. 



which attribute^ a preponderating- part to the- attack on the vahiable 

 elements nnule by the macrophages is not a mere phuisible specuhition, 

 but rests on numerous and exact facts. It Avoukl be interestinfr to 

 penetrate moi-e deeply into the causes of this drama which is being 

 played within our own organism and which occasions such serious 

 evils. Unhappily science is not sufficiently informed to satisfy an 

 investigating spirit otherwise than by the aid of hypotheses. 



III. 



It has often been said that old age is a kind of disease. In fact the 

 great resemblance between these states is incontestable. Among the 

 maladies to which an organism is subject there is a considerable group 

 that manifest themselves in the form of atrophies. Sometimes it is 

 an atrophy of muscles Avhich occasions a considerable weakness in 

 the voluntary movements and in which we find proliferation of the 

 nuclei, as in the muscles of old people. Atrophic maladies of the 

 kidneys and of the liver are numerous, and in these we find a dis- 

 appearance of the glandular tissue and its replacement by connective 

 tissues the same as we find in old age. Atrophy of the osseous sub- 

 stance produced by giant cells often occurs in the course of certain 

 maladies. In all these examples the more ])rofoundly we study the 

 lesions the more Ave become convinced of their similarity to those 

 which take place during old age. 



Although the cause of many of the atrophic nuiladies is still un- 

 known, thei'e are nevertheless some whose origin is sufficiently estab- 

 lished. Thus, among the atrophies of the nniscles, we may cite that 

 whicli is induced by the parasitism of trichina\ The penetration of 

 these minute worms into the muscular fascicles produces lesions that 

 occasion multiplication of muscular nuclei and a destruction of the 

 contractile substance. 



The analogy with the atroj^hy of muscles is undeniable. The 

 atrophic mahulies of glandular apparatuses, such as the liver and the 

 kidneys, are often occasioned by poisoning by alcohol, lead, and other 

 chemical su.bstances or they may be occasioned by some infectious 

 microbic malady. Again, it is this latter cause which often leads 

 to the destruction of the osseous substance. In certain infectious 

 maladies like tuberculosis and lejorosy the bacilli penetrate into the 

 bones and succeed in forming there infectious foci. These bacilli 

 are, however, incapable by themselves of dissolving and destroying 

 the osseous substance, but the products that esca]:)e from them into 

 the bones exercise an irritating action upon the giant cells which set 

 to work to eat away the osseous lamellae impregnated Avith lime. The 

 tuberculous or lei)r()us agent plays, therefore, only an intermediate 

 part in the atrophy of the skeleton, Avhich is inmiediately caused, as in 



