ON THE VEGETABLE CHEESE, NATTO. 71 
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 flocculent 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 
