350 LIFE AND DEATH. 



origin of the scleroses which engender chronic 

 diseases, we find that they are due to the action of 

 various poisons, among which syphihtic poison and 

 the immoderate use of alcohol^ take the first place. 

 These are also the usual causes of senile degenera- 

 tion. But there must be some other, some very 

 general cause to explain the universality of the' 

 process of senescence. Metchnikoff thinks that he 

 has found this cause in the microbes which swarm in 

 man's digestive tube, particularly in the large in- 

 testine. Their number is enormous. Strassburger 

 has given an approximate calculation, but words fail 

 to express it. We have to imagine a figure followed 

 by fifteen zeros. This microbic flora is composed of 

 "bacilli" and of "cocci," and comprises a third of 

 the rejected matter. It produces slow poisons, 

 which, being at once reabsorbed, pass into the blood 

 and provoke the constant irritation from which 

 results arterio-sclerosis and the universal sclerosis 

 of old age. Instead of enjoying a healthy and 

 normal old age, in which the faculties of ripening 

 years are preserved, we drag out a diminished life, 

 a kind of chronic disease, which is ordinary old age. 

 This is due, according to Metchnikofi", to the para- 

 sitism and the symbiosis of microbic flora, lodged in 

 a part of the economy in which it finds all the con- 

 ditions favourable to its prolific expansion. Such is 

 the specious theory, held to the verge of intrepidity, 

 by which this investigator explains the misery of our 

 old age, and which inspires him with the ^dea of a 

 remedy. For his observations conclude with a 

 regime, a series of prescriptions by which the author 

 fancies that life may be lengthened and the evils of 

 old age swept from our path. The dangerous flora 



