476 SUMMARY OF CURRENT RESEARCHES RELATING TO 



retting) of flax is a purely biological process accomplished by tbe action 

 of tbe common saprophytic bacteria and moulds of the air. Ordinary 

 methods of isolation demonstrated the presence of the following organisms 

 upon the flax stalks retted in the open air : — B. coli communis, B. mesen- 

 tericus fuscus, B. fluoresceins liquefaciens, B. mycoides, B. subtilis, Micro- 

 coccus roseus, Streptothrix Forsteri, Penicillium glaucum, Mucor mucedo, 

 Cladosporium herbarum. Of these organisms the B. coli, B. mesentericus, 

 and the Cladosporium herbarum are the most numerous and most active 

 in the process of retting. The author placed stalks of flax in large glass 

 tubes (50 cm. long"), together with a few centimetres of dilute broth or 

 beer wort, sterilised tubes and contents by repeated heatings at 110° C> 

 and inoculated with pure cultivations of these different organisms (a 

 higher temperature than 110° C. was found to produce a partial dis- 

 sociation of the flax fibres). At the end of about twelve days retting 

 was complete, but Hauman found that in general the moulds were much 

 more energetic in their action than the bacteria, attacking the cellulose 

 of the fibres and destroying their solidity. 



That the process of retting is due to microbial activity was shown 

 by exposing two handfuls of flax, side by side, to atmospheric influences 

 for about a month. The one was not interfered with, the other was 

 placed in an atmosphere of formaldehyde every two or three days to 

 destroy bacterial life. At the end of the experiment the first bundle 

 was completely retted, whilst the process had not even started in the 

 second. 



Source of Acid Organisms of Milk.* — E. Burr details the investi- 

 gations he pursued in order to determine whether the acid organisms 

 lound in milk exist in the cow's udder, or are present in the dust and 

 air and only contaminate the milk during or after milking. 



The technique adopted was to draw small quantities of milk from 

 a single cow into sterile 10 ccm. tubes at the beginning and close of 

 milking, taking every precaution against air-borne contamination, at the 

 same time filling a sterilised litre jar with the same milk but without 

 observing such precautions. He then plated the milk samples, using 

 plain gelatin with 3 p.c. lactose and coloured with litmus, that being 

 the most suitable medium. The milk in the sterile tubes contained 

 500 micro-organisms per ccm., and did not include the B. acidi lactici ; 

 it did not curdle for 8 or 10 days. Unripened cream from the milk 

 drawn in the sterile pail contained about 161 million organisms, and 

 when ripened, about 268 millions, including the B. acidi lactici I., the 

 B. acidi lactici II., and B. lactis aerogenes. 



In a second series of experiments, specimens of milk were collected 

 as in the previous experiments, and in addition gelatin plates were 

 exposed under the cow for varying short periods during the process of 

 milking. All the plates contained the B. acidi lactici and B. lactis 

 aerogenes, showing that the acid organisms are probably an outside 

 contamination. 



Further experiments comprised the collection of samples of milk on 

 three successive days from seventy different cows under conditions cal- 

 culated to prevent accidental contamination, the results similarly point- 



* Centralbl. Bakt., 2 U Abt., viii. (1902) pp. 236-41. 



