374 r.eh.wiour of iiacti'ikia. 



Summary. 



Differences in tolerance of different bacteria for arseiuc 

 are very marked. Many which are fairly tolerant of arsenate 

 are relatively sensitive to arsenite. Certain groups are character- 

 isticiilly sensitive, e.g., the subtilis group, of which the four 

 leading representatives were tested, and all found intolerant of 

 0.05 per cent, of AsgO.-j as sodium arsenite in broth. Other 

 groujis, notably the piitidum family, can tolerate from 10 to 20 

 times this concentration, some members growing freely in i per 

 cent, arsenite broth. The colon-typhoid group is sensitive as a 

 family, but has at least one outstanding exception in B. arscnre- 

 ducens, and other resistant members probably exist. Resistance 

 to arsenic is therefore not a rigorous group characteristic, 

 although it is probably as characteristic as any other biochemical 

 feature, and might find a place in diagnostic bacteriology. Apart 

 from the members of the putidum group, five highly resistant 

 bacteria {i.e.. non-sporulating rod forms) are described, but not 

 named. 



Of four cocci tested, three were found sensitive, and one 

 tolerant. Two members of the streptothrix group were both 

 sensitive. Yeasts and luonhis generally show a high degree of 

 tolerance. 



Although over a dozen arsenic resistant species of bacteria 

 were examined, only two showed any chemical activity towards 

 arsenic; the earlier described B. arseiio.vydans. which oxidises 

 arsenite to arsenate, and B. arsenreducens, which reduces arsenate 

 to arsenite. The others were merely tolerant. There is no dis- 

 cernable relationshi]) between arsenate reduction and nitrate 

 reduction. 



Arsenite resistant bacteria are infrequent in soil, but fairly 

 frequent in faeces. About 10 per cent of the bacterial count of 

 fresh stable manure were found moderately tolerant, and about 

 I per cent, highly tolerant. In arsenical dipping tanks an auto- 

 matic enriching of resistant faecal bacteria, and su])pression (or 

 metamorphosis ) of sensitive forms takes i)lace. 



Vktp:kinar>- Rkskarcii Lahoratorii-.s. 

 Pretoria. 



Paper from Meg ass. — A mill is about to be erected 

 at Olaa, Hawaii, for the purpose of manufacturing paper from 

 megass, the refuse cane from sugar factories. The out])ut of 

 paper will be 16^ tons daily, but that will absorb only about one- 

 tenth of the ([uantity of megass available. It is hoped that if 

 megass paper turns out as well as exi)ected, all the megass ])ro- 

 duced luay in course of time be utilised, so that e\entually there 

 may be something like 165 tons of ])a])er turned out daily from 

 the Olaa mills. If the venture meets with success, other ])lanta- 

 tions may follow suit, and in course of time develop in Hawaii an 

 industry almost as important as the sugar manufacture. 



