TRANSACTIONS OF SECTION M. 775 
Pot culture experiments with barley have been carried out, and show that 
with many soils large increases of crop may be obtained by the use of moderate 
applications of caustic lime. With some soils (garden soils, rich in carbonate) 
plant growth is adversely affected by larger doses, but the authors are not pre- 
pared at present to advance an explanation of the phenomenon. 
Pot Cultures with Barley in Limed Soils. 
Yields of Dry Matter (Untreated Crop 100). 
Caustic Lime applied (per cent.) Meas, ) 
Soil ‘ 
GeO | 02 | 03 | o4 | 8 | 10 | = 10 
Rothamsted . | 100 | 209 | 224 | 300 | 276'| 199 | 14 101 
Chelsea. . ./| 100 | 99 | 115 112 | 111 | 105 | 94 96 
Craibstone . . | 100 | 96 | 110 | 116 | 132 | 135 | 160 | 118 
Millbrook . . | 100 | 184 | 230 | 271 | — | 8% | 15 | 14 
2. Investigations on the Protozoa of Soil. By T. Goovry. 
This paper dealt with two pieces of work carried out to ascertain the part 
played by protozoa in the soil, and is the outcome of the theory advanced by 
Russell and Hutchinson, viz., that the protozoa in the soil act directly as a 
factor limiting bacterial activity, and therefore affect indirectly soil fertility. 
The first investigation consisted of an attempt to get out from the soil, by a 
rapid method, the first protozoa to appear in a hay-infusion culture of soil. 
It was inferred that these would, in all probability, be the forms leading an 
active existence in the soil, if such were present. A method was finally devised 
by means of which the ciliated protozoa appearing first in such a culture were 
obtained quite quickly. These forms were chiefly Colpoda, and in no case did 
they appear until an hour and a half to two hours after inoculation. This 
period of time is practically the same as that taken for the excystation of 
Colpoda from its resting-cysts. Moreover, the protoplasm of these earliest- 
occurring forms contained no food vacuoles and resembled very closely in 
appearance that of recently excysted Colpoda. This suggested that they had © 
come out from cysts on the addition of the soil to the hay-infusion. The con- 
clusion drawn from these results was that the ciliated protozoa are only present 
in the soil in an encysted condition and cannot therefore function as the factor 
limiting bacterial activity. 
The second investigation dealt with the effects of partial sterilisation on two 
old soils which had been stored in bottles for many years at Rothamsted, one 
since 1846 and the other since 1870. The former yielded no protozoa under 
cultural conditions, whilst the latter only gave ameba and flagellates as its 
protozoan fauna. A set of four bottles of each of these soils was put up and 
partially sterilised by means of volatile antiseptics, one bottle of each set being 
left untreated. Counts of bacteria were made over a period of about 240 days. 
It was found that the 1846 soil showed no phenomena which accompany a normal 
soil when partially sterilised. The bacteria in the untreated soil did not remain 
low in numbers, but on the contrary reached and maintained a higher figure 
than the bacteria of the treated soils. 
The 1870 soil on the other hand showed the usual phenomena accompanying 
partial sterilisation. The untreated soil kept low in bacterial numbers whilst 
the treated soils showed high bacterial numbers. In the treated soils also the 
rotozoa were killed off. The conclusion drawn from these experiments is that 
in the 1846 soil there is no factor limiting bacterial activity, whilst in the 1870 
soil containing ameeba and flagellates the limiting factor is present. 
