ItO 
w. CATTON GRASBY, F.L.S. : 
cessation of the nitrifying process, but it was evident 
that the increase in the amount of ammonia was not 
simply clue to tnis fact. Extended research enabled 
them to demonstrate that partial sterilisation, while it 
destroyed many forms of bacterial and other microscopical 
life, did not completely destroy the bacteria responsible 
for the production of ammonia, and that after treatment 
these bacteria increased with marvellous rapidity, which 
accounted for the increase in ammonia. Investigation into 
the reason of this showed that in ordinary soil micro-organism 
of the protozoa family, of relatively large size as compared 
to the ammonia producing bacteria, devoured the latter 
and prevented their rapid increase. Partial sterilisation 
completely destroyed the protozoa, thus allowing the 
ammonia- producing bacteria a free field for rapid increase - 
Saprophytic micro-organisms tend to increase the 
fertility of the soil, because they produce ammonia, fix 
nitrogen, and so on, although sonre of them are, under 
certain conditions, injurious because they bring about a 
liberation of free nitrogen. A second class of organic life 
known as phagocytes consume living bacteria. These two 
classes of organisms act and react on one another, according 
to the same law which operates among the more highly 
organised animals and plants all around us. This discovery 
explains facts which had long been known, that heating 
and drying the soil results in increased productiveness. 
Dr. Hutchison, writing to Mr. Grasby, stated that : 
“ exposure of soil to a moist heat of 130 to 140 degrees Fah. for from one 
to two hours has been shown to be sufficient to destroy protozoa in soils, 
while higher temperatures tend to increase fertility by gradual decomposi- 
tion of the organic matter of the soil.” 
Professor Warrington, in his book on the “ Physical 
Properties of the Soil,” states that for the greatest amount 
of solar heat to reach the earth the air must not only be 
clear but dry. In the case of the bare dry soil freely ex- ' 
posed to the sky the range of temperature at the surface is 
very great — far greater than that of the air above it. Sir 
J. F. W. Herschel sunk a thermometer 4 in. deep in South 
Africa and observed the temperature to rise 150 deg. Fah. 
Schubler placed a thermometer one-twelfth of an inch 
below the surface of soil in Germany, and the highest 
temperature observed during two years was 158 deg. Fah. 
The same experimenter found that the black soil quite 
dry became 13 to 15 deg. warmer than white soil. 
On February 1st of the year (1911) the official record 
at Guildford gave a shade temperature of 107.7 deg- Fah. 
Between 1 and 2 o’clock that day he took tecords in his 
garden with a dairy thermometer, which may be considered 
