APPENDIX 339 



X. MICROBES OF SOIL, WATER, AND AIR. 



Concerning our previous remarks on the microbes of 

 the soil, it may be added that Keimers * has recently 

 ascertained the number of microbes in soil at various 

 depths. For instance 



A sample of soil at surface contained 2,564,800 microbes per cc. 



,, ,, 2 yards below surface contained 23,100 ,, ,, 



>. 3* 6,170 



4J 1,580 



>. 6 



It has been already stated that Bacillus tetani has been 

 found in soil ; and Mace 2 has recently found B. typhosus 

 in various samples of soil. B. tuberculosis and B. coli 

 communis have also been found in soil. On the other 

 hand, De Giaxa 3 has shown that soil is a bad medium 

 for the preservation of B. cholerce Asiaticce, this being 

 due to the large number of saprophytic species present, 

 whose struggle for existence interferes with the vitality 

 of the cholera microbe. In fact, this is an important 

 example of the survival of the fittest, for De Giaxa has 

 proved that soil per se has no detrimental action on the 

 cholera microbe. 



If soil is a bad medium for the preservation of some 

 forms, water (especially when polluted) is a better 

 medium for others. At the recent Congres d' Hygiene 

 Ouvriere 4 M. Gautier exhibited illustrations of the 

 typhoid, carbuncle, cholera, and diphtheritic microbes, 

 with many others, in Seine water ; 5 and the dis- 

 tinguished chemist said to householders and others, 



1 Zeitschrift fiir Hygiene, vol. vii. 



- Comptes Rendus, vol. cvi. p. 1564 ; and his Traite Pratique 

 de Bacteriologie (1-891), p. 717. 



3 Annales de Microyraphie (1890) vol. ii. 



4 Held in Paris during April 1892. 



5 Paris drinking-water. 



