and Magazine of the Ceylon Agricultural Society.— Oct, 1910. 



867 



order to destroy any bacteria it might contain, 

 had thereby gained greatly in fertility, as though 

 some largo addition of fertiliser had been made 

 to it. Though these observations had been 

 repeated in variouB times and places, they were 

 generally ignored, because of the difficulty of 

 forming any explanation : a fact was not a fact 

 until it fitted into a theory. But within tho last 

 five years the subject had received some con- 

 siderable attention until the facts became esta- 

 blished beyond question. Approximately the 

 crop became doubled if the soil had first beer, 

 heated to a temperature of 70 deg. to 100 deg. 

 for two hours, while treatment for 48 hours with 

 the vapour of toluene, chloroform, &c, followed 

 by a complete volatilisation of the antiseptic, 

 brought about an increase of 30 per cent, or so. 

 Moreover, when the material so grown was ana- 

 lysed, the plants were found to have taken very 

 much larger quantities of nitrogen and other 

 plant foods from the treated soil; hence the in- 

 crease of growth must be due to larger nutri- 

 ment and not to mere stimulus. 



Successful Experiments at Rothamsted. 



The explanation, however, remained in doubt 

 until it had been recently cleared up by Drs. 

 Russell and Hutchinson, working in the Roth- 

 amsted laboratory. In the first place, they found 

 that the soil which had been put through the 

 treatment was chemically characterised by an 

 exceptional accumulation of ammonia, to an 

 extent that would account for the increased fer- 

 tility. At the same time it was found that the 

 treatment did not effect complete sterilisation 

 of the soil, though it caused at the outset a 

 great reduction in the numbers of bacteria 

 present. This reduction was only temporary, 

 for as soon as the soil was watered and left to 

 itself, the bacteria increased to a degree that was 

 never attained under normal conditions. For 

 example, one of the Rothamsted soils employed 

 contained normally about seven million bacteria 

 per gram — a number which remained compara- 

 tively constant under ordinary conditions. Hea- 

 ting reduced the numbers to 400 per gram, 

 but tour days later they had risen to six million, 

 after which they increased to over 40 million 

 per gram. The accumulation of ammonia in the 

 treated soils was accounted for by this increase 

 in the number of bacteria, because the two pro" 

 cesses went on at about the same rate. The ques- 

 tion now remaining was, What had given this 

 tremendous stimulus to the multiplication of 

 the ammonia-making bacteria?— and by various 

 steps the two investigators reached the conclu- 

 sion that the cause was not to be sought in any 

 stimulus supplied by the heating process, but 

 that the normal soil contained some negative 

 factor which limited the multiplication of tho 

 bacteria therein. 



Curious Interacting Forces. 

 Examination along these lines then showed 

 that all soils contained unsuspected groups of 

 large organisms of the protozoa clasp, which fed 

 upon living bacteria. These were killed oft' by 

 heating or treatment by antiseptics, and on 

 their removal the bacteria, which partially es- 

 caped the treatment, and were now relieved 

 from attack, increased to the enormous degree 

 that he had specified. According to this theory 



the fertility of a soil containing a given store of 

 nitrogen compounds was limited by the rate at 

 which these nitrogen compounds could be con- 

 verted into ammonia, which, in its turn, de- 

 pended upon the number of bacteria present 

 effecting the change, and these numbers were 

 kept down by the larger organisms preying upon 

 the bacteria. The larger organisms could be 

 removed by suitable treatment, whereupon a 

 new level of ammonia-production, and therefore 

 of fertility, was rapidly attained. Curiously 

 enough one of the most striking of the larger 

 organisms was an amoeba akin to the white 

 corpuscles of the blood — the phagocytes, which, 

 according to Metchnikoff'f theory, preserved us 

 from fever and inflammation by devouring such 

 intrusive bacteria as find entrance in the blood. 

 The two cases were, howevor, reversed : in the 

 blood the bacteria were deadly, and the amoeba 

 therefore beneficial, whereas in the soil the 

 bacteria were indispensable and the amceba 

 became noxious beasts of prey. 



Since the publication of these views of the 

 functions of protozoa in the soil confirmatory 

 evidence had been derived from various sources. 

 For example, men who grew cucumbers, toma- 

 toes, and other plants under glass were accus- 

 tomed to make up extremely rich soils for the 

 intensive culture they practised, but, despite 

 tho enormous amount of manure they employed, 

 they found it impossible to use the same soil for 

 more than two years. Then they were compelled 

 to introduce soil newly taken from a field and 

 enriched with fresh manure. Several of those 

 growers here had observed that a good baking 

 of this used soil restored its value again ; in 

 fact, it became too rich and began to supply the 

 plant with an excessive amount of nitrogen. 



Evidently there was no simple solution to the 

 question— What was the cause of the fertility of 

 the soil? There was no single factor to which 

 they could point as the cause ; instead they hail 

 indicated a number of factors any one of which 

 might at a given time become a limiting factor 

 and determine the growth of the plant. All that 

 science could do as yet was to ascertain the ex- 

 istence of these factors one by one and bring 

 them successively under control ; but, though 

 they had been able to increase production in 

 various directions, they were still far from being 

 able to disentangle all the interacting forces 

 whose resultant was represented by the crop. 

 — London Times, Sept. 2. 



COPRA IN THE PHILIPPINES. 



Bright Prospect for the Coconut Industry. 



Recently compiledlfigures, says the Philippine 

 Agricultural Review, show that the copra in- 

 dustry in the islands is in a most healthy con- 

 dition. The production of copra in the Philip- 

 pines for the past four years is given as follows - 



1906 927,942 piculs. 



1907 844,909 „ 



1908 1,345,166 „ 



1909 ... ... 1,658,724 ,. 



Total 4,776,741 „ „ 



Approximately 103,000 tons, or about one- 

 third of the world's production, are grown iu 



