A Sugar Bacterium. 



11 



It seemed impossible to test the first suggestion on such minute cells, 

 but attempts were made to test the second one by the following 

 experiment : — 



The bacterium was grown in saccharose yeast extract inside a porce- 

 lain filter plunged into the same solution ; the gelatinous matrix was 

 formed in abundance inside the filter, but none was developed outside 

 although the liquids communicated freely through the pores of the 

 filter. Of course the reply may be made that an enzyme of this 

 nature may be unable to traverse the fine pores, and the question 

 must be regarded as still open. 



These gelatinous sheaths or " capsules " are now known in many 

 Schizomycetes, among the best examples being that of B. vermiforme* 

 and Leuconostoc, j and it is now pretty generally agreed that these 

 sheaths are composed of dextran,j: and Liesenberg and Zopf§ made a 

 curious observation with reference to its formation • they found that 

 the addition of. calcium chloride favoured the development of the 

 sheath. 



Calcium Chloride. 



Zopf's paper suggested that we should test the effect of CaCl2, and 

 accordingly solutions of Liebig's extract, peptone-saccharon, and CaClo 

 were tried. 



In the slightly alkaline liquid at 32° a mere shimmering turbidity 

 was observed in twenty-four hours, and in four days a dense gelatinous 

 clot formed below the turbid liquid. 



At 23° the alkaline liquid showed similar turbidity on the second 

 day, and had formed very little gelatinous deposit in four days. In a 

 week, however, it resembled that at 32° C. 



The same solution slightly acidulated with a drop of HC1 was 

 slightly more turbid in twenty-four hours, but very little of the jelly 

 formed even in a week. 



At the end of the week both set of tubes were distinctly acid, and 

 evidently the formation of the jelly is favoured by the slight alkalinity 

 of CaCl 2 . 



This seemed to strengthen the supposition that our bacteiium may 

 be the same as Van Tieghem's Leuconostoc, but a close comparison does 

 not bear out this view. 



It is nevertheless interesting to observe that Leuconostoc inverts 

 saccharose, and only forms sheaths in presence of that sugar or of 

 grape-sugar ; that these sheaths are explained as the swollen cell-walls, 

 and many other features exist in common with our form. 



* Marshall Ward, ' Phil. Trans.,' B, 1892, loc. cit. 



f Tan Tieghem, 'Ann. des Sci. Nat.,' 6th Series, Bot., vol. 4, 1878. 



X Scheibler, ' Yereinzeitsch. f. Kubenzncker Ind.,' (1874), p. 24. 



§ 1 Beitr. z. Phys. u. Morph. niedcrer Organismen,' Heft 1, 1892, p. 1. 



