1 Jaw., 1898.] QUEENSLAND AGRICULTURAL JOURNAL. 61 
From the great analogy between the nitrogenous substances in plant and 
animal life, it will be seen that to a great extent the value of a plant or its 
seeds as a food for animals depends on the amount of nitrogen contained 
therein. From the vegetable alyuminoids found in the seeds of the cereals 
wheat, oats, rye, &c.; in leguminous plants and their seeds, as beans, peas, 
clover, lucerne, cow peas, &ec.; in the roots and tubers of turnips, mangels, 
potatoes, &c.—are formed by the process of digestion after these foods have been 
consumed by the animals, the albuminoids found in milk, flesh, blood, &e. Even 
horn, hair, and fat are formed from these albuminoids. Albuminoids thus supply 
nearly everything required by the animal body, not only the flesh and blood, &c., 
but also force and heat. The amides and other nitrogenous compounds found in 
plants, and forming part of the food, are simply burnt in the animal body, and 
give, like fat, only heat and force. The nitrogen introduced into the animal 
body is not all used up for the building-up of this body, but a part of it is 
removed with other products of oxidation of waste material and old tissue in 
the form of urea; this nitrogen compound contains about half its weight of 
nitrogen. 
The nitrogen compounds found in plants play also an important part in the 
germination of their seeds, and form part of the nourishment of the young plants, 
No crop will flourish without a suflicient supply of nitrogen, and this 
supply of nitrogen may be obtained from the following sources :— 
1. Atmospheric nitrogen. 
2. Nitrates, nitrites, and ammonia found in the atmosphere, and washed 
down and carried into the soil by rain. 
3. Nitrites and nitrates formed in the soil by the process of nitrification of 
organic nitrogen compounds always found in vegetable residue and humus of 
the soil. hese nitrogen compounds contain the nitrogen in an inert form, 
in which it cannot be made use of by the plants. Certain microbes, however, 
decompose these organic nitrogen compounds, and transform them first into 
nitrites and eventually into nitrates. The activity of these nitrifying bacteria 
js increased by moisture, warmth, and looseness of the soil. Too much 
moisture, however, is detrimental; and in wet, badly-drained soil, for the want 
of access of air, nitrification will not take place. 
4, Nitrogenous manures, as farmyard manure, oilcake, and artificial 
manures, containing nitrogen as sulphate of ammonia and nitrate of soda. 
ASSIMILATION OF ATMOSPHERIC NITROGEN. 
Until the year 1886, all scientists, with the exception of G. Ville, declared 
that free nitrogen gas was not used as a food by plants. Hellriegel discovered 
in that year that certain leguminous plants could assimilate free nitrogen, with 
the help of micro-organisms or bacteria living in the nodules found on their 
roots. The leguminous plants differ in this respect from the large order of 
Graminex, to which all our cereals and grasses belong, and which depend for 
their nitrogen supply exclusively on the nitrogen compounds contained in the 
soil.” Crops of Leguminose—as lucerne, clovers, lupines, cow peas—are not 
only quite independent of the nitrogen compounds present in the soil, but are 
capable of accumulating nitrogen, and thus enriching the soil, thereby improving 
it for a crop of cereals following the leguminous crop. ; 
Hellriegel’s experiments were continued by others. Professor Nobbe 
made cultivations of these bacteria living on the nodules of various Legumi- 
nose. Although the bacteria obtained from various plants cannot be 
distinguished from each other, their action shows a great difference, and special 
cultivations brought into the market under the name “nitragin” are recom- 
mended for each crop. ‘This nitragin is contained in little bottles, about half- 
filled with a little brown jelly, on which a white mould is noticeable. Each 
bottle is sufficient for about half-an-acre. The contents are dissolved in 
lukewarm water, and the seeds to be sown sprinkled with this water; or about 
‘56 1b. of soil are moistened with the liquid, and the soil spread over the field to 
be sown and worked in to a depth of about 3 inches. 
