On the Significance of the Nitrates Contained in 
Plants for Animals and Men. 
BY 
f 
T. Ishizuka ? Nögakushi. 
As the presence of nitrates in the food is of more influence 
upon the well-being of animals and men than is often supposed, it 
is well to discuss such circumstances as relate to the amount of 
stored up nitrates in plants ; these are principally : 
a) . Intensity of nitrification in the soil. 
b) . The amount of rain removing the nitrates from the soil. 
The amount of nitrates formed in the soil depends, of course, 
above all upon the amount of ammonia present ; in the second 
place upon the condition of the soil. 
D eher ain noticed a great influence of the kind of soil upon 
the intensity of nitrification : a porous soil formed more than 
double as much of nitrate as a less porous one ; a clayey soil 
would admit less aération, therefore would be also less favourable 
for nitrification (Ann. Agronom. 21, 353, 1895). 
In the third place the development of the microbes of nitri¬ 
fication (Nitrosomonas and Nitromonas ) depend not only upon 
climate, and mechanical condition of the soil, but also upon the 
presence of certain chemical compounds ; thus it was found by 
Dumont that the increase of potassium salts in a soil and the 
simultaneous presence of humus and calcium carbonate favour 
the development of the nitrifying microbes, and therefore the 
production of nitrites from ammonia which very soon pass into 
nitrates in the soil. 
Furthermore, the amount of rain must have a great influence 
upon the amount of nitrates, as these are not absorbed by the 
soil. Heavy rains combined with thorough drainage of the field 
therefore deprive the soil well nigh completely of the nitrates 
present. On the other hand, frequent small showers will merely 
promote the energy of nitrification, and a larger amount of 
nitrates will accumulate, because of the rain water in this case 
not draining away, but simply evaporating again from the soil. 
