544 OLD AGE. 



tinal contents secrete their products for a long time, thus setting up 

 a chronic poisoning. It is exactly among these products that we 

 should seek for the cause of the weakening of our noble elements 

 and the stimulation of the destructive activity of the macrophages. 

 It is true that certain poisons once absorbed by the organism initiate 

 the production of counter poisons Thus, Ehrlich, after having 

 caused his mice to SAvallow quantities of vegetable toxines, ricine and 

 abrine, proved that the blood of these animals became the best anti- 

 dote against these poisons. The human organism after absorbing 

 for years the microbic products elaborated in the intestines might 

 indeed thus acquire an immimity with regard to them. This sup- 

 position is very probable, but it does not at all apply to a whole 

 series of microbic poisons, such as the phenolic substances, the 

 amnioniacal salts, and others, for their absorption occasions no 

 production of counter poisons. 



According to the hypothesis we are advancing, the principal 

 phenomena of old age depend upon the indirect action of microbes 

 that become collected in our digestive tube. And, since the wearing 

 away of the substance of the bones in tuberculosis and leprosy is 

 effected by osteoclasts excited by the poisons derived from the bacilli 

 characteristic of those tAvo maladies, so the same wearing away of 

 the bones may come from a stimulation of the same osteoclasts by the 

 poisons of intestinal microbes. If this is the case, our organism con- 

 tains within itself the cause of its own destruction, in the same way 

 that grapes carry upon their surface the germs of the ferments that 

 set up alcoholic fermentation by destroying the sugar the fruits 

 contain. 



This hypothesis rests upon a great number of well-established 

 facts, but it lacks direct proof, which can only be furnished by inves- 

 tigations carried on for long years. In this imperfect state it 

 becomes necessary to bring together as many arguments as possible 

 in order to justify our supposition. 



If it is really intestinal microbes that are the cause of our senile 

 atrophy, we must believe that the more the flora of the intestines is 

 reduced the fewer manifestations of old age there will be. 



If we compare an old mammal with an old bird we are at once 

 struck Avith the great difference in their external appearance. An old 

 horse or an old dog can easily be recognized by its ugliness, its lazy 

 movements, its worn teeth, its lusterless hair turned white on certain 

 portions of the body. A dog of 12 to 15 years shows very markedly 

 all these signs of senile decrepitude. Birds keep their age much bet- 

 ter and longer than mammals do. An aged duck, more than 20 years 

 old, is alert in its movements and does not show externally any sign of 

 its advanced age. Parrots and parroquets also remain for long years 

 in a very youthful state. A little parroquet from 15 to 19 years old, 



