52 INFECTIONS OF THE DIGESTIVE TRACT 



concluded that from four and five-tenths to ten per cent, 

 of the faecal bacteria are capable of growing on the 

 common culture media. Klein got only about one per 

 cent, to grow; Schmidt and Strasberger, basing their 

 estimates on a different method of procedure, which in- 

 volved weighing masses of bacteria in order to avoid the 

 errors incidental to counting, came to the conclusion that 

 only about 0.07 per cent, of the bacteria are viable. It 

 is, however, easy to see that none of these methods can 

 claim to give even approximately correct results, because 

 we have in the nursling's faeces many anaerobic bacteria 

 which grow only under special conditions, and acidophile 

 bacteria which require special media for their cultiva- 

 tion, and these special conditions have not yet been 

 furnished by those who have made numerical estimates. 

 Moreover, it is extremely probable that on their 

 way through the large intestine many bacteria undergo 

 autolysis and wholly disappear. Hence the problem 

 of determining the fate of the bacteria in their descent 

 through the nursling's colon is one beset with diffi- 

 culties so considerable as to make numerical com- 

 parisons an unpromising field for study. There can, 

 however, be no doubt that, as already stated, the living 

 bacteria of the intestine usually undergo a marked 

 diminution in numbers on their passage through the colon 

 and that a large proportion of them seen under the 

 microscope in preparations from the faeces are not viable, 

 even on anaerobic plates. The histological signs of dis- 

 integration are often visible. Among the causes of the 

 death of intestinal bacteria, under normal conditions, 



