Feb., 1913. The Queensland Naturalist. 247 
amongst the subjects qualifying for their profession, in the 
interests of the sanitary branch of it especially have argued 
that “ this is not less an age of bacteria, than it is an age of 
electricity, and have maintained also that better sanitation 
would result from thorough fundamental instruction relating 
to matter in the living state" (cf. “ Science/’ 1896, p. 301 ) 
Again, the study of animal and plant life has a very 
important bearing on rural industries, pastoral, agriculture 
and horticultural alike. This proposition is too obvious to 
need the support of any detailed statement for their scope 
is immediately identified with it ; and indeed it might be 
maintained without difficulty — that other conditions being 
equal, the success achieved by any country in its rural indus- 
tries has been proportionate to the extent to which it has 
applied the principles of the biological sciences in their 
development. In this respect the Aphorism of Bacon thus 
applies : — " Scientia et potentia humana in idem concidunt.” 
And the important position that they are assigned, in any 
up-to-date institution, for training the pioneers of further 
advance in these rural industries, is an eloquent although 
indirect testimony to the same effect. 
Before proceeding further, however, I will refer to two 
or three facts showing the bearing of the science of living 
things on this great department of human enterprise. 
1. The Soil. Baron J. Von Liebig — ^one who has been 
regarded as the founder of agronomic science, taught us, 
in his " Natural Laws of Husbandry," and in other of his 
publications, that plants contained certain mineral constituents 
whose number was fixed, but that varied in the extent of 
their occurrence, and that the soil was a kind of trough 
that either originally contained those as required, or might 
receive them, and that these bodies — the food of plants — - 
were fixed therein chemically or physically, but the latter 
only were available for their requirements. He further 
insisted on what he styled the law of the minimum : — “Every 
field (he wrote) contains a maximum of one or several, and 
a minimttm of other nutritive substances. It is by the 
minimum that the crops are governed, be it lime, potash, 
nitrogen, phosphoric acid, magnesia, or any other mineral 
constituent, it regulates and determines the amount or 
continuance of the crops." (Liebig — J. Von, “ The Natural 
Laws of Husbandry. — Ed. J. Blyth, p. 213, Lond. 1863.) 
But it is now known that the merits of the soil as a crop 
producer are not merely determined by a knowledge of its 
chemical constituents, but that its tenure and structure have 
to be taken into account, as well as its conditions as regards 
temperature and moisture ; but more than this — and it is 
my point — biological science teaches us that the soil is the 
theatre, for the continuous energetic and varied display of 
