MICROBES AS FACTORS IN SOCIETY. ic 5 



strange and remarkable similarity of action, mentioned by Claude 

 Bernard in his last notes, and now demonstrated by M. Duclaux 

 and his pupils. The climax of these complex chemical reactions 

 is reached in the humus, which is compared by M. Duclaux to a 

 laboratory in ceaseless activity, into which the primary matter is 

 continuously entering to be worked up there and transformed into 

 new products assimilable by the plant. 



Availing itself of the action of an external force, the solar 

 light and heat, this laboratory employs as its workmen the mi- 

 crobes, which only are capable of carrying the complicated task 

 to a good result. Fixers of nitrogen, for example, in the nodular 

 formations of the leguminous plants, preparers of nitrates, and 

 constantly producing soluble organic substances at the expense 

 of insoluble matters, the microbes work untiringly in this vast 

 abode of chemical transformations. 



Yet more : as old as the living world, contemporaries of the 

 earliest generations of plants, microbes have contributed in a 

 powerful way to the constitution and formation of the geological 

 strata. Peat, which later becomes coal, has been formed by the 

 action of microbes ; they have been the agents in the complex 

 processes of precipitation by which the immense masses of vari- 

 ous limestones have been formed ; they have played a part in 

 other reactions from which deposits of iron, sulphur, and most of 

 the metals have resulted. This enumeration might be very much 

 extended. These innumerable and strong chemical actions, an- 

 cient as some of them are, still play an immense part, which is 

 absolutely necessary to the existence of the social medium. From 

 the point of view solely of producer of coal and preparer of iron, 

 the microbe justifies its claim to be an agent indispensable to the 

 life of all society. But its function is still more complex and 

 extended. 



The chemical work of microbes is often used industrially by 

 man. Two examples in which this is done may be taken as typ- 

 ical. Indigo is extracted from a plant which is cultivated chiefly 

 in India, Japan, and Central America. The plant contains a 

 sugar, indiglucin, which is separated by washing in warm water, 

 and is then subjected to a special fermentation. The microbe 

 splits it into indigotin and glucose. The indigotin, which is col- 

 orless, is oxidized, still by means of a microbial! reaction, and is 

 transformed into blue indigo. This preparation would be impos- 

 sible without these special microbial! reactions. 



Another example of the chemical activity of microbes is fur- 

 nished in the preparation of opium for smoking. The juice of 

 the poppy, from which opium is derived, was till lately fermented 

 in tubs to give it the desired qualities. Recently M. Calmette, of 

 Saigon, discovered that this transformation was due to the Asper 



