450 !W. M. ('. I'ntUT. <)n 



heiteu," de Bary has shown th;it oxalic acid is secreted by the hypha' 

 >f Pi-.i-.n .<>!> r,>f in, a in when living a- a parasite, and that thi* a.-iil 

 as a toxin in killing and plasmolysing the protoplasm. Wehmer 

 has found that ./>/ /<////"< niif,- ami /'<////////>/. ,/lini,-,!,,, also form 

 oxalic acid when growing in a sugar-containing solution. Oxalic 

 acid, being an unavoidable product in the metabolism of the higher 

 plants ; i" ( l ; dso in some fungi, it seemed reasonable to suppose that 

 it might be found as a similar product in the life of bacteria. With 

 this idea I tested the juice expressed from a rotten turnip, and 

 found, on addition of calcium chloride, a precipitate which proved to 

 be calcium oxalate. Cultures were then undertaken to test for the 

 presence of oxalic acid as a product from P. <l.<ti-ii>-t<ni.<. A broth, 

 made by steaming small pieces of actively growing turnips until soft, 

 was neutralised by an excess of calcium carbonate and filtered ; it was 

 then allowed to stand overnight, when a further deposition of calcium 

 took place ; it was then again filtered, clarified with the white of an egg, 

 steamed, filtered, and drawn into four flasks, each containing 150 c.c., 

 which were sterilised. A solution was thus obtained free from any oxalic 

 acid which might have been present in the tissues of the turnip. Two 

 of the flasks were inoculated with P. <//-.--//-r////*x on August i'8th. In 

 twenty-four hours they became turbid, and after four days were tested 

 and found to contain oxalic acid ; while the control flasks showed no 

 evidence of this acid, and remained perfectly clear. 



P. ilestrudanx also sets up an oxalic fermentation in Pasteur's 

 solution. A litre of Pasteur's solution with cane sugar was made up 

 and divided into four flasks, each of which was carefully sterilised and 

 one sown with P. de*ti'>t<i'trt.<. After twenty-four hours the liquid in the 

 inoculated flask, which was previously perfectly clear, became cloudy, 

 and after a week quite opaque; 10 c.c. of this, when treated with a 

 solution of calcium chloride, in the presence of acetic acid, at once 

 showed a precipitate of calcium oxalate, which increased on being 

 warmed. Another 10 c.c. of the original solution, which had )>een 

 kept sterile during the same period, remained quite clear on treatment 

 with the same re-agents. P. <//->7/W /*.> thus sets up an oxalic fer- 

 mentation in a sugar containing liquid. It has also been found that 

 carbon di-oxide is given off during the proci 



When treated with alcohol, the Pasteur solution, in which P. dt 

 /"/(s had been growing for eight days, yielded a white flocculent 

 precipitate which contained the cytase. The oxalic acid, however, 

 remained in solution, and was deposited as the calcium salt on addition 

 of calcium chloride. This calcium precipitate, when mixed with 

 manganese di-oxide and treated with sulphuric acid, yielded carbonic 

 acid, which furnishes a further confirmatory test of the presence of 

 oxalic acid. The precipitation by alcohol affords a ready method of 

 separating the toxin (oxalic acid) from the cytase, and this explains 



