RETTING 121 



Controlled warm water retting has undoubtedly come 

 to stay, and many new arrangements for this purpose are 

 constantly being inaugurated. 



103. The Rossi Process of Retting. This process was devised 

 by Prof. Rossi, Flax depot, Sarthe Dept., France. 



The underlying feature of his principle consists in decom- 

 posing the pectinous compounds between the flax fibres and 

 the stem, by a ferment resultant from the action of aerobic 

 bacilli for which the presence of air is indispensible, as dis- 

 tinguished from the usual method of retting where the ferment 

 producing agent is of the anaerobic type, and which can operate 

 in a medium free from air. 



The pure culture of aerobic bacilli is prepared by, and 

 obtained from Professor Rossi in small hermetically sealed 

 glass tubes 2J to 3 in. in length and J by | in. diameter. 

 Each tube also contains a small quantity of flax straw and 

 " culture bouillon," but is kept intact until required for rapid 

 propagation in the incubators. The incubators are zinc 

 tanks, approximately 2| ft. in height and 2 ft. in width. In 

 these the culture bouillon (food) is prepared. The operation 

 consists in placing a small quantity of flax straw in the tanks 

 and boiling in water for about 50 minutes. The resultant 

 product is a gelatinous substance or " culture bouillon/' 

 sterilized and freed from foreign micro-organisms. The tem- 

 perature of this bouillon is then allowed to fall to 30 C. 

 (86 F.) at which degree it is maintained. At this stage the 

 pure culture of bacilli from one of the glass tubes is emptied 

 into the incubator. 



These conditions of temperature and supply of food are 

 considered by Professor Rossi to be most favourable for a 

 rapid propagation of the added pure culture of aerobic bacilli. 

 The maximum increase in pure culture is completed in a 

 period of 48 hours. 



Each incubator contains a sufficient quantity of pure 

 aerobic culture to immediately start the retting in a vat con- 

 taining about ten tons of flax straw. The contents of the 



