234 OUTLINES OF BACTEEIOLOGY 



Retting of Flax. Flax is prepared from certain fibres of the plant 

 Linaria vulgaris. These fibres are bound together by the middle 

 lamella (Fig. 128), which is the name given to the material with which 

 the fibres are bound together, and which differs in constitution from 

 the fibres themselves. The object of retting is to effect the solution 

 of the middle lamella, without injuring the fibres. This is accomplished 

 either by dew-retting or by water -retting. In the former method the 

 plants are spread on the ground and exposed to the influence of 

 the atmosphere, whilst in the latter method the plants, wrapped up in 



bundles, are steeped, roots downwards, in 

 water-tanks. In both cases, the solution 

 of the middle lamella is accomplished 

 through the activity of certain bacteria, 

 which feed on this binding substance 

 without injuring the fibres. One of these 

 bacteria has been isolated by Winograd- 

 sky. This is a bacillus with individuals 



FIG. ^.-Diagrammatic repre- 10-1 5 /* long and 1 fl broad, which forms 



mid t di t eiameiia fibroUS " CClls ' "^ = s P ores > becoming at the same time tad- 

 pole-shaped. It grows anaerobically and 



in the presence of nitrogenous food is able to ferment saccharose, 

 lactose, and starch. A patent has been obtained in the United 

 States for a method whereby the retting can be performed in a few 

 days. This method consists in steeping the plants, after cleaning, in 

 a liquid containing substances which favour the growth of this bacillus, 

 the latter in the form of a pure culture being added to the liquid. It is 

 claimed that this method shortens the retting to about a quarter of the 

 time required in the other methods. There can be no doubt that this 

 is a step in the right direction, and it is surprising that so little atten- 

 tion has been paid to the possibilities presented by pure culture 

 methods of treatment. 



Retting of Hemp, Jute, and Cocoanut Fibre. Hemp is obtained from 

 the fibres of various plants, e.g. Datisca, Cannabina and Musa texilis. 

 Jute is a fibrous substance resembling hemp but is obtained from the 

 bark of Indian plants allied to the lime-tree. It is largely used in the 

 manufacture of carpets, bagging, curtains, etc. Both hemp and jute 

 are prepared by water-retting, the fibres or the bark being left exposed 

 in rivers or tanks. The fibre used in the manufacture of cocoanut 

 matting is prepared from the outer husk of the cocoanut the article sold 

 in the shops is the inner part only of the whole nut and its prepara- 

 tion also is accomplished by the same method. A large field of work is 



