November, 190S.J 



4(57 



Scientific Agricullure. 



manures. Investigations into the chemi- 

 cal constitution of plants determined 

 their food requirements and laid the basis 

 of rational manuring, and led to the utili- 

 sation of many waste products for that 

 purpose. Chemistry has in other wa.ys 

 much enhanced agriculture, and is, with- 

 out doubt, the science which has influ- 

 enced modern agriculture to a greater 

 extent than any of the others. The 

 dairymen throughout the world have 

 to thank the bacteriologist for many 

 advantages ; and but for La vail, the 

 physicist, thinking out the separator 

 in his laboratory, dairying would not 

 be profitable in warm climates. Be- 

 tween the botanist and the patho- 

 logist means were found to produce 

 rust-resisting wheats, besides ameli- 

 orating other plant diseases. By study- 

 ing the life history of insects the ento- 

 mologists have found proper ways of 

 suppressing or cheeking insect pests. 

 The improved knowledge of the metal- 

 lurgist made it possible to produce 

 cheaper steel and other metals, and 

 thereby cheapend and improved farm im- 

 plements and machinery. When in the 

 sixties of last century a disease broke 

 out amongst the silkworms in Southern 

 France, killing every caterpillar where- 

 everit made its appearance, and rapidly 

 spreading through almost every estab- 

 lishment for the rearing of silkworms, 

 thereby bringing thousands of silkworm 

 rearers to the brink of starvation, and 

 jeopardising the whole silk industry 

 which gave employment to several 

 millions of people, it was science that 

 came to their rescue through the 

 medium of great Pasteur. By the atte- 

 nuated virus of anthrax, descovered also 

 by Pasteur, the means of preventing 

 the terrible disease was disclosed, and 

 thereby Australia has benefited to an 

 enormous extent. Many other similar 

 instances might be quoted in which 

 agriculture, has benefited by scientific 

 lesearch, 



Bacteria. 



From the fact that a number of 

 bacteria are disease-producing in man, 

 beast, and birds and plants, the whole 

 tribe of these minute plants have 

 acquired a detestable reputation in 

 popular opinion. Such a general con- 

 demnatory opinion they do not, how- 

 ever, deserve. The mischievous bacteria 

 and allied forms of micro-organisms, 

 terrible as they manifest themselves at 

 times, are numerically insignificant in 

 comparison with the great number 

 which may be termed either directly or 

 indirectly beneficial to the higher 

 forms of life, and still more with those 

 which are decidedly harmless, and 

 whose role in the economy of nature is 



not understood at present. Many hun- 

 dreds are wel-known, and their char- 

 acteristics have been worked out, and as 

 researches progress they are constantly 

 added to. Being of very delicate 

 structure they are very sensitive to • 

 external conditions, especially to the 

 presence or absence of oxygen, which 

 striking characteristic divides them 

 into two distinct groups. Those which 

 require oxygen for their growth, and 

 prosper ill without it, are called 

 aerobic, and those upon which oxygen 

 has a toxic effect, are called anaerobic 

 bacteria. 



Nitrogen. 



In order to fully undei stand the im- 

 portance of the bacteria to be specially 

 discussed, it is necessary to make a few 

 remarks regarding the element nitrogen, 

 which is absolutely needed as a food by 

 all animated nature. 



Nitrogen in its simple form is a gas 

 abundantly present in our atmosphere, 

 where it is practically inert, and acts 

 as a diluent of oxygen, the element 

 required by all breathing beings. In 

 this simple form it is otherwise perfect- 

 ly useless to either plants or anmials. 

 Moreover in this state it will not readily 

 combine even with oxygen, almost the 

 only element it attaches itself to when 

 in the elementary state. Plants, how- 

 ever, cannot utilise it unless it has been 

 oxidised into nitric acid. In that form 

 only is it assimilable by plants which 

 possess the power of elaborating it into 

 other complex compounds known by the 

 term of organic-nitrogen compounds, 

 and albuminoids, in which forms it 

 serves as food for animals. The fact 

 must not be lost sight of — that whilst 

 animals require organic nitrogen com- 

 pounds for their nutrition, plants cannot 

 directly utilise again the compounds 

 they elaborate, but require them simpli- 

 fied into nitric acid. This is done by 

 bacteria, a group of which are called 



Nitrifying Bacteria. 

 As soon as a plant or animal is dead it 

 is attacked by bacteria. whos6 function 

 it is to reduce it into the elements from 

 which it was built. The same applies to 

 any dead organic substance, the voidiugs 

 of animals, offal of any kind, stable 

 manure, &c. These bacteria are the 

 putrifying organisms, of which there are 

 a number of forms, and which are the 

 forerunners of the nitrifying bacteria. 

 In the process of decay different gases 

 are evolved during the progress of 

 fermentation. Some bacteria liberate 

 nitrogen, and others ammonia, from the 

 organic nitrogenous compounds. The 

 nitrogen so evolved is lost in the air, 



