794 SUMMABY OF CURRENT RESEARCHES RELATING TO 



including forty species, of wliicli only tliree are marine. In Microchsete, 

 Scytonema (including Petalonema), HassalUa, and Tolypoihrix, the tricliomes 

 are solitary in their sheaths ; in Desmonema, Hydrocoryne, and Diplocolon, 

 from two to six trichomes are frequently included in a common sheath. 



Beggiatoa alba.* — Prof. W. Hillhouse finds this organism in the 

 coccus form and in that of rodlets and spirals, and displaying swarming 

 and even creeping movements like those of the Oscillariaceae. It may be 

 grown for laboratory purposes on fragments of (vulcanized) indiarubber 

 tubing kept in water, on which it will usually appear spontaneously after 

 the lapse of a few months. 



Chemical Action of Bacterium aceti.f — Mr. A. J. Brown gives some 

 further notes on the chemical action of Bacterium aceti. The oxidizing 

 action of the pure ferment on mannitol has been described, showing that 

 this carbohydrate is completely decomposed, and that a sugar (levulose) is 

 the main product formed from it. As dulcitol is an isomerid of mannitol, 

 it appeared interesting to ascertain if B. aceti had any action on it, more 

 especially as, according to Carlet, dulcitol yields a CeHigOo sugar on oxida- 

 tion with dilute nitric acid. In the several experiments made, however, not 

 the least action of the ferment on the dissolved dulcitol could be detected. 



Action of B. aceti on glycol. — The action of B. aceti on a 2 per cent, 

 solution of the dihydric alcohol glycol was next studied. The solution was 

 sterilized and inoculated with the ferment in the usual manner. At first 

 the ferment grew freely, but the action was evidently over in five weeks' 

 time. On opening the flask the solution was found to be slightly but 

 distinctly acid ; a portion was evaporated to a small bulk and filtered, and 

 the absence proved of any acid giving an insoluble lime salt. The 

 rest of the solution was boiled with calcic carbonate, filtered, and the 

 lime salt so formed precipitated by excess of alcohol. The precipitate 

 was dried, and a determination of the lime made. From the amount of 

 lime present it seemed probable that this precipitate was glycollate of 

 calcium, and a second experiment confirmed this opinion. The action of 

 the ferment on glycol may be represented simply thus : — 



CH2(OH)-CH2(OH)+ 0, = CH2(0H)-C00H + OB.,. 



Action of B. aceti on glycerol, — The action of B. aceti on a 5 per cent, 

 solution of the trihydric alcohol glycerol was next tried. From the first 

 the bacteria increased with remarkable freedom, and after the expiration of 

 eleven weeks, when the flask was opened, there ajjpeared to be a larger 

 growth of the ferment, both in the liquid and as a deposit at the bottom, 

 than had previously been observed in any other experiment with B. aceti. 

 At the end of the experiment, titration of a portion of the solution showed 

 that there was O'lll per cent, acid present calculated as acetic acid. It 

 appeared from the several experiments made that the action of B. aceti on 

 glycerol is to decompose it into carbonic acid and water, the only other 

 product of the action being a very small amount of an acid the nature of 

 which is undetermined. 



Action of B. aceti on erytTirol. — Solutions of this tetrahydric alcohol in 

 yeast-water, both with and without calcic carbonate, were submitted to the 

 action of B. aceti ; but although the ferment grew freely, no action on the 

 erythrol could be detected. The fact that erythrol is not acted on by B. aceti 

 is interesting, because this same substance is oxidized by platinum-black to 

 erythric acid. 



It \vill be noticed, therefore, that not only is B. aceti unable in some 



* Kep. Brit. Assoc. Birmingham Meeting, 1886, p. 701, 

 t Journ. Cliem. Soc. Lond., 1887— Trans., pp. 638-42. 



