ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 475 



■with the B. flaorescens, only those from plot IV. were attacked, and 

 those but feebly, and further passages did not appear to increase the 

 virulence of the bacilli, whilst the beetroot appears to be quite immune. 

 In default of potatoes from the experimental plots, some grown in 

 neighbouring fields were next used, but no growth could at first be 

 obtained upon them. If, however, the resistance of the potatoes was 

 previously reduced by soaking in soda solution (1 in 1000) for 60 minutes, 

 growth, especially marked in the case of the B. fluorescens liquefaciens, 

 was obtained, and destruction of the potato tissue to a depth of 8-15 mm. 

 resulted in two days. Successive passages again exalted the virulence 

 of these organisms, so that finally they would attack all varieties of 

 potato. 



Microscopically, the tissues of the potatoes infected with the 

 B. fluorescens, which, it should be noted, was isolated in the first in- 

 stance from a rotten potato and possessed an appreciable initial viru- 

 lence, showed disintegration of the parenchyma and coagulation of the 

 internal protoplasm associated with the production of an alkaline 

 reaction. The juice expressed from potato and turnip cultivations and 

 filtered contained a diastase pectinase, which dissolved pectose : this 

 enzyme is destroyed at 62° C. The substance which coagulates the 

 protoplasm appears to be a mixture of acetic and lactic acids and resists 

 exposure to a temperature of 100° C. 



The author concludes from his experiments that an excess of nitro- 

 genised manure or of lime predisposes the tubercles to bacterial invasion, 

 while phosphates tend to increase the natural resistance of carrots and 

 turnips. 



Bacterial Flora of Mont Blanc* — Binot undertook a study of the 

 bacterial flora of (1) the glaciers; (2) water; and (3) air, at several 

 points on Mont Blanc during the months of August and September 

 1900. He found that organisms were chiefly limited to the surface of 

 the glaciers, 1 or 2 per ccm., chiefly orgauisms of slight resistance ; 

 in the depths were found sporing bacteria, streptotricheas, and sporing 

 moulds. The author states that he isolated a virulent race of the 

 B. pyocyaneus from the ice of the summit. At the foot of the glacier 

 the number of surface bacteria is larger, e.g. Mer de Glace, 6-65 per ccm. 

 The numbers were distinctly smaller on surfaces exposed to the sun's 

 rays than in situations protected from the sun. Fresh snow is practically 

 sterile, as much as 8 ccm. of material failing to yield a single colony. 



The waters from the glaciers contained extremely few bacteria, some 

 only 3-8 per ccm. The air also contains but few micro-organisms, the 

 numbers per cubic metre diminishing progressively as the valleys are left 

 behind, and average 6 on the Grand Plateau. One experiment at least 

 failed to demonstrate a single germ in that volume of air. 



As a result of this research, -the author isolated about 300 either new 

 or undetermined species of bacteria, of which he has already worked out 

 about one-third. 



Retting of Flax.f — Hauman communicates a preliminary note on 

 the bacteriological study of the factors concerned in the aerobic retting 

 of flax. His observations lead him to conclude that the air retting (dew 



* Comptes Eendus, csxxiv. (1902) pp. 673-6. t Tom. cit., pp. 11G3-6. 



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