136 BACTERIA 



The former is practised in Russia, and consists in spreading 

 the flax on the grass and exposing it to the influence of dew 

 rain, air, and light. The result is a soft and silky fibre. 

 Water-retting is accomplished by means of steeping the flax 

 in bundles, roots downwards, in tanks or ponds. In ten to 

 fourteen days, according to the weather, fermentation sets 

 in, and breaks the " shore " or " shive " from the fibre, and 

 the process is complete. This is always done by the aid 

 of bacteria, which, under the favourable circumstances, mul- 

 tiply rapidly, and cause decomposition of the pectin resinous 

 matter. The same operation occurs in jute and hemp. 

 Sponges, too, are cleared in this manner by the rotting of 

 the organic matter in their interstices. The preparation of 

 indigo from the indigo plant is brought about by a special 

 bacterium found on the leaves. If the leaves are sterilised, 

 no fermentation occurs, and no indigo is formed. Tohacco- 

 curing is also in part due to decomposition bacteria, and 

 several bacteriologists have experimented independently in 

 fermenting tobacco leaves by the action of pure cultures 

 obtained from tobacco of the finest quality. 



In all these applications we have advanced only the first 

 stage of the journey. Nevertheless, here, as in nature on a 

 big scale in the formation of fertile soils and coal-measures, 

 we find bacteria silently at work, achieving great ends by 

 co-operating in countless hordes. 



