USE OF BACTERIA IN THE ARTS. 43 



separate them by any mechanical means. The 

 whole cellular substance of the stem is bound 

 together by some cementing materials which hold 

 it in a compact mass, probably a salt of calcium 

 and pectinic acid. The art of preparing flax is 

 a process of getting rid of the worthless wood 

 fibres and preserving the valuable, longer, tougher, 

 and more valuable fibres, which are then made 

 into linen. But to separate them it is necessary 

 first to soften the whole tissue. This is always 

 done through the aid of bacteria. The flax stems, 

 after proper preparation, are exposed to the ac- 

 tion of moisture and heat, which soon develops a 

 rapid bacterial growth. Sometimes this is done 

 by simply exposing the flax to the dew and rain 

 and allowing it to lie thus exposed for some time. 

 By another process the stems are completely im- 

 mersed in water and allowed to remain for ten to 

 fourteen days. By a third process the water in 

 which the flax is immersed is heated from 75 to 

 90 F., with the addition of certain chemicals, for 

 some fifty to sixty hours. In all cases the effect 

 is the same. The moisture and the heat cause a 

 growth of bacteria which proceeds with more or 

 less rapidity according to the temperature and 

 other conditions. A putrefactive fermentation is 

 thus set up which softens the gummy substance 

 holding the fibres together. The process is known 

 as "retting," and after it is completed the fibres 

 are easily isolated from each other. A purely 

 mechanical process now easily separates the valu- 

 able fibres from the wood fibres. The whole pro- 

 cess is a typical fermentation. A disagreeable 

 odour arises from the fermenting flax, and the 

 liquid after the fermentation is filled with prod- 

 ucts which make valuable manure. The process 



