264 The " Ginger-leer Plant ." [Dec. 17. 



the gelatinous sheaths and the escape of the bacteria from them were 

 observed in hanging-drop cultures, and are figured and described by 

 the author. The conditions for the development of the gelatinous 

 sheaths and therefore of the coherent brain-like masses of the 

 Schizomycete are a saccharine acid medium and absence of oxygen. 

 The process occurs best in carbon dioxide : it is suppressed in bouillon, 

 and in neutral solutions in hydrogen, though the organism grows in 

 the free, non-sheathed, motile form under these conditions. 



The behaviour of pure cultures of the bacteria in as complete a 

 vacuum as could be produced by a good mercury pump, worked daily, 

 and even several times a day for several weeks, is also noteworthy. 

 The author records his thanks to his friend and colleague Professor 

 McLeod for much assistance in regard to this apparatus. The develop- 

 ment of the sheaths is apparently indefinitely postponed in vacua, but 

 the organism increased, and each time the pump was set going an 

 appreciable quantity of carbon dioxide was obtained. In vacuum 

 tubes the same gas was evolved, and eventually attained a pressure 

 sufficient to burst some of the tubes. The quantity of carbon dioxide 

 evolved daily by the action of the bacterium alone, however, is small 

 compared with that disengaged when the organism is working in 

 concert with the symbiotic yeast ; in the latter case the pressure of the 

 gas became so dangerous that the author had to abandon the use of 

 sealed tubes. 



The products of the fermentation due to the Schizomycete have not 

 yet been fully determined in detail ; lactic acid, or some allied com- 

 pound, seems to be the chief result, but there are probably other 

 bodies as well. 



The author owes acknowledgment to Dr. Matthews, of Cooper's 

 Hill, for advice and assistance in examining the products of these 

 fermentations. 



The pink yeast-like form proved to be very interesting. It has 

 nothing to do with the " ginger-beer plant " proper, though it was 

 invariably met with as a foreign intruder in the specimens. The 

 author identifies it with a form described by Hansen, in 1879;* 

 unfortunately the original is in Danish, but the figures are so good 

 that little doubt is entertained as to the identity. It is also probably 

 the same as Fresenius' Cryptococcus glutinis in one of its forms. It is 

 not a Saccharomycete, and does not ferment like a yeast; it is 

 aerobian. 



The chief discovery of interest was that in hanging drops the 

 author traced the evolution of this "rose-yeast" into a large com- 

 plex mycelium, bearing conidia, and so like some of the Basidio- 

 mycetes that it may almost certainly be regarded as a degraded or 



* ' Organismer i 6l og Olurt,' Copenhagen, 1879. 



