476 ISHIZUKA ; ON THE SIGNIFICANCE OF THE NITRATES 
Moreover, shallow soils are more easily deprived of the 
nitrates by the same amount of rain than deep soils ; and finally 
a great influence will be exerted by the temperature, as in sum¬ 
mer the nitrification is more intense than in winter. Thus we 
observe a local and temporal influence upon the amount of nitrates 
present in the soil, and the great differences Berthelot (1) observed 
in regard to the quantity of nitrates in plants thus finds a simple 
explanation. 
Countries with regular and copious summer rains will show 
also less nitrates in the plants than countries with rather dry 
summers, while again in desert-soils nitrates are not found at all, 
because of no bacillus being able to thrive in the absence of 
water. 
The noxious qualities of vegetable food, rich in nitrates, for 
animals have been recognized by Lawes and Gilbert, the illu¬ 
strious investigators of Rothamsted, England. I quote from the 
lecture of Henry Gilbert delivered in America in Nov. 1893 the 
following passage : 
“ Then, again, as generally more or less of the 
nitrogen in root will exist as nitrate, it will so far not 
only have no food value, but it may be positively injuri¬ 
ous. It may be added that, other things being equal, 
the higher the percentage of nitrogen in roots the lower, 
as a rule, will be the proportion of it as albuminoids, 
and the higher that as amides and as nitrate, etc. 
Further in direct experiments at Rothamsted with sheep 
feeding on roots alone, it was found that while the 
animals even gained in weight on ripe roots, low in 
nitrogen, they actually lost on roots that were less ripe, 
high in nitrogen, and doubtless containing a larger pro¬ 
portion of their nitrogen as non-albuminoid compounds.” 
It is true that nitrates by themselves have not a very noxious 
effect on animals as it requires about 2.5 g. of potassium nitrate for 
I kilo of body-weight of an animal to bring on death, but there 
(i) Berthelot found that the amount of nitrates may vary from o to 15 % in potato, 
from o to 2.8 % o in wheat, from o to 15 % in Amarantus . (Chem Centralbl. 1884, 
639)- 
The amount in turnips and beets was found to vary between 0.5 —3.5 % of the dry 
matter {Eber may er, Physiologische Chemie der Pflanzen). 
