ON THE VEGETABLE CHEESE, NATTO. 



reactions of peptone and consisted for the most part of this 

 substance. 



The above mentioned part (b) was treated with ammo- 

 niacal solution of silver nitrate whereby a small amount of a 

 white precipitate was obtained which was collected on a filter 

 and washed with dilute ammoniacal solution of silver nitrate, 

 then dissolved in warm nitric acid of sp. gr. 1,1 with the addition 

 of little urea. Upon cooling, microscopical needles were obtain- 

 ed, which proved to be a mixture of the silver compound of 

 guanine and of hypoxanthin. After the removal of the silver 

 with sulphuretted hydrogen, filtering and evaporating with the 

 addition of a little ammonia, a residue was obtained, soluble 

 with great difficulty in water and alcohol but easily soluble in 

 mineral acids. It was treated with ammonia whereby a part 

 was dissolved and a part not. The latter gave the sharp reac- 

 tion of Capranica for guanine. When dried with nitric acid in a 

 platinum dish it gave a yellow residue, which turned red on the 

 addition of soda. The former, i. e., the soluble part was ob- 

 tained by evaporationg the ammoniacal liquor. When evaporat- 

 ed in a platinum dish with nitric acid, and the residue treated 

 with caustic potash, no coloration took place. The reaction 

 of Weidel and of Capranica did not leave any doubt that this 

 substance was hypoxanthin, but there was contained also xanthin 

 in the cheese. This was obtained by adding ammonia to the 

 filtrate separated from the first crystallisation of the guanine 

 and hypoxanthin silver compounds. By adding ammonia, a 

 yellowish fiocculent precipitate was obtained from which the 

 silver was removed by sulphuretted hydrogen. The filtrate then 

 evaporated to dryness left a faintly yellowish powder slightly 

 soluble in water, insoluble in alcohol and ether, but easily soluble 

 in alkalies and acids. On treating it with nitric acid a yellow 

 residue was obtained turning red upon the addition of soda 

 and purple on heating. The reaction of Hoppe-Seyler and 

 Weidel left no doubt that this substance was xanthin. Wheth- 

 er these substances of the xanthin series were formed by the 

 bacterial action during twenty-four hours in the warmed cellar 

 is doubtful. I think it is more probable that they were origi- 

 nally present in the soya bean. But there can be no doubt 

 that a large portion of peptone, and also leucin and tyrosin 



