286 
Supptement to the '^frojncal Agriculturist.^' [Oct, 2, 1893. 
occupying conspicuous places, and he had there- 
lore embraced this opportunity of laying his 
\ieAvs before a learned society for discussion, 
lie regretted that the opponents of the advancing 
science had not, although specially invited, put 
in an appearance, because it was important, in 
tlie interests of science, and of its students, 
that the truth be known ; and if this Society 
should express an adverse opinion of his posi- 
tion, he would be only too glad to accept their 
verdict. Mr. Hunter then xjroceeded to discuss 
the commonly obtaining doctrine of retention of 
jjlant food by silicates and oxides, and, in 
passing, referred to Professor Way's doctrines of 
the order of absorption of oxides by silicates in 
the soil. The tenor of his remarks was to show 
that certain truths had been established by the 
practice and experience of the forefathers who 
tilled the soil, and that the many ravines had 
been bridged over by scientists who were unprac- 
tical and ill-fitted for the task, with the result 
that the foundations were now being demolished, 
even in the face of unbecoming opposition from 
quarters where only encouragement ouglit to 
have been expected. He then proceeded to show 
that a sterilised soil, i.e., a soil in which germ 
life had been destroyed without in any way 
altering its purely^ chemical composition or 
constitution, was practically ?<«retentive, while 
the same soil in its normal state possessed its 
retaining power ; therefore they were entitled to 
assume that the retention of the essential 
constituents of plant food was not to any material 
extent due to purely chemical interchanges, but 
was rather due to the biological condition of 
soils — to germ life — that in fact, a germless soil 
must be an unfertile soil, unless they could grow 
their crops in soils under water-culture condi- 
tions, which was for the present impossible. Mr. 
Hunter then discussed the commonly described 
doctrines of cappillarity in soils ; this theory 
implied the for-ever-existing multitudinous tubes, 
bringing water from the subsoil. lie asked the 
question, How was it possible for water to be 
rising through water-pipes by capillarity in soils 
whose drains — natural or artificial — Were acting 
as exhaust pumps at the lower ends of the capil- 
lary tubes ? He then referred to the opinions of 
physicists in regard to capillarity in organic 
matter, and said that physicists who had expressed 
opinions upon this point had yet to learn that 
decomposing organic matter in the soil was germ 
occupied, and that many of the conditions 
exhibited by soils, which had been ascribed to 
physical phenomena, were almost wholly ac- 
counted for by those biological conditions which 
are inseparable from decomposition of organic 
matters in soils. Again, he asked, How could 
scientists account for the occurrence of different 
compounds of iron existing in the subsoil as 
compared with the surface soil, if those much- 
lauded capillary water-pipes existed ? It is 
generally conceded that in the subsoil we have 
ferrous salts, which are generally described as 
soluble ; while in the surface soil of fertile laud 
the iron is in the ferric state and insoluble. If 
capillary tubes exist which perform this wonderful 
function of bringing water from the subsoil to 
the surface, they must— in virtue of the well 
known laws of diffusion— bring ferrous salts lo- 
tbe surface, and that is just what even the 
advocates of capillarity deny; therefore, his 
opponents should fight their own doctrines first 
before attempting to assail his. 
A capillary soil Mr. Hunter described as a 
water-logged soil, and only serviceable for con- 
version into a skating rink or curling pond. He 
then referred to the recently-introduced theory 
of soil mulching or hoeing, by whicli the capil- 
lary lubes were broken, and evaporation from 
the surface or upper ends of the tubes prevented. 
If tlie water pipes were non-existing, then this 
theory was absurd, but even supposing this kind 
of capillarity were a reality, tlie evaporation 
must only be prevented by a breaking of tbv 
continuity of the mass, wliereby conduction of 
heat would be lessened, but most certainly not 
because the tops of water pipes were broken, for 
the duration of the fracture would l»e measur- 
able by seconds ; moreover, soils and plants— 
whether the lower plants or genns, or the higher 
plants — required aeration, and that is incompati- 
l)le with the capillary tubes described in every 
text-book on agricultural science which he liad 
perused. The subject of drainnyt was then refer- 
red to, and in this connection Mr. Hunter iwinted 
to the composition of the atmospliere, or ordinary 
air, as compared with that of the soil atmosphere, 
the former containing 0 02, or take it as "04 per 
cent., while soil atmosphere contained, it might 
be 30 to 60 or more per cent, of carbon dioxide. 
This carbon dioxide of the air was invariably 
claimed as the great soil solvent — the provider 
of foods to plants ; but how could even O-l per 
cent, in the air be considered so potent, when in 
the soil so enormously greater a proportion exist- 
ed ? Soil organisms he claimed to be the pro- 
viders of foods to plants, and the high proportion 
of carbon dioxide in soils was a product of 
the life's work of those germs, and that unless 
drains — natural or artificial — were in the soil to 
drain away this carbon dioxide, no ordinary 
plant could live, because, while these plants can 
be grown to perfection under water-culture 
conditions in water, they could not grow in an 
atmosphere of carbon dioxide, therefore the 
primaiy functions of drains in soils was the 
removal of ' carbonic acid.' 
Tlie selectii-e jjou ert! of plants were next dealt 
with, and Mr. Hunter showed that grass seeds 
sown on different soils might produce a crop 
containing 10 per cent., or it might contain 40 per 
cent, of silica in the ash. How did this agree 
he asked, with the obtaining doctrines of selec- 
tion!' That fact was of itself sufficient to 
annihilate the present theories, but the most 
convincing proof of all was the leguminosre 
which were employed, as the most convincing 
proofs of powers of selection in plants. Mr. 
Hunter emphasised, without any hesitation, that 
the composition of the leguminosse was in no 
way due to selective power, but was wholly 
ascribdble, or nearly so, to the symbiotic growths 
on the roots — growths which, he believed, were 
first described by Mr. McAlpijie, and as ' wart- 
like excrescences,' and that long before Hellriegel, 
Wilfarth, or any other worker in this department 
had been heard of. 
]\Ir. Hunter then dealt with soil organisms, and 
spoke of those which he and Mr. McAlpine had 
isolated ; and in tliis connection he referred to 
the efforts which a number of ifvotkers iiaU beea 
