Élie Metchnikoff

A prefatory note presents the book as the work of a specialist in the science of life, addressed to the gravest problems of humanity: life, sex, death and the fear of death¹. The contents list shows the method. It takes organs such as the large intestine and asks what use they serve. It also lists the harm done by intestinal microbes and the frequency of cancer of the large intestine and of the stomach². In the held text the argument also covers sexuality. Metchnikoff holds that its disharmonies lead to aberrations, and that this is why religions came to denounce human nature as vile³.

Loeb reports that Metchnikoff studied natural death in the silkworm butterfly. The adults lack the organs for taking up food, so their lives are short. Metchnikoff recorded that they could live twenty-three days, with an average of 15.6 days for males and 16.6 for females⁴. Loeb adds that seventy-five per cent of them had no parasitic fauna or flora in the intestine, and that the changes of old age in man were absent from their tissues. Metchnikoff was inclined to think an excretion retained in the body poisoned the animal⁵.

Loeb set Metchnikoff against Minot. Minot had argued that death is the price metazoa pay for the greater differentiation of their cells, and Loeb called this purely metaphorical. Loeb wrote that he was inclined to follow Metchnikoff. On this view natural death comes from a poison accidentally or unavoidably formed in the body, or from some structural shortcoming⁶.