Vol. X. No. 239. 



THE AGRICULTURAL NEWS. 



201 



Bacteria and Phosphoric Acid in the Soil. 



An abstract of e.xporiments that have been carried 

 out for the purpose of ascertaining the part that is 

 played by bacteria in the change of insoluble phos- 

 phoric acid into soluble phosphoric acid in the soil is 

 contained in the Journal of the Board of Agriculture 

 for March 1911, p. 1020. In the investigation, air free 

 from carbon dioxide and ammonia was passed through 

 sifted and sterilized soil kept in the dark at a tempera- 

 ture of 8(5 F. In one case, the soil was inoculated with 

 a bacterial culture, while in that of the control this 

 was not done. The energy of the bacteria was measured 

 by ascertaining the amount of ammonia and carbon 

 dioxide that was given off from the soil containing 

 them. 



The results showed that the quantity of soluble 

 phosphoric acid in the soil was actually reduced to an 

 important extent: there was, however, a continuous 

 change of insoluble into soluble acid, but it w'as 

 masked by the fact that its rate was smaller than that 

 of the opposite process. The rate of formation of 

 carbon dioxide indicated that the energy of the bacteria 

 was greatest after the first five to ten days of the 

 experiment. In the course of two months, this energy 

 graduall}' weakened, and the total amount of carbon 

 dioxide produced in the period was found to be 

 between ten and twenty times greater where the 

 bacteria were present, than in the case of sterile soils. 



A Companion to Blackie's Tropical Readers. 



A booklet bearing this title has been prepared in 

 Jamaica by E. J. Wortley, F.C.S., with the object of 

 providing hints for jjractical work in connexion with 

 the information presented in Blackus Tropical Read- 

 erfi. Books I and II. The contents include (1) the 

 Introduction, comprising general hints to teachers and 

 pupils, as well as on the use of apparatus; (2) the study 

 of animal life; (3) the study of economic plants: 

 (4) experiments in practical work in cunnexion with ani- 

 mals and plant life, based on the information in Book I: 

 (.5) experiments and practical work of the same kind, 

 but referring to the matter in Book II; (6) the school 

 garden: and (7) an appendix having reference to the 

 botanical names of a few of the commoner plants. 



The information in relation to the use of appara- 

 tus is somewhat scanty, and an inexperienced teacher 

 would find himself in some difficulty, if he were depend- 

 ent alone upon this for his work. The hints supplied 

 in the two succeeding sections should be useful in giving 

 teachers a knowledge of the way in which lessons should 

 be conducted. Equally useful is the second sub-section of 

 section IV, presenting short instructions for simple ex- 

 periments relating to plant life: although it is unfortun- 

 ate that the illustrations, which are generall}' the same as 

 those in the Readers, depict mostly English types of 

 plants instead of those with which the teacher and 

 pupil are likely to be familiar: this circumstance applies 

 as well to sub-section II of section Y. The sub-sec- 

 tion on Health contains usefully concise information; it 

 is doubtful, however, that even the author himself would 



obtain success if he followed exactly the instructions 

 for some of the experiments given under the heading 

 Water, The Air We Breathe and Why the Wind Blows. 

 Altogether, this is a very useful little book, and 

 foims an almost indispensable teacher's companion to 

 the Tropical Readers. 



Cassava from Brazil. 



It is stated in the Bulletin Agricole, Mauritius, 

 for March 1911, that, according to a British Consular 

 Report on the trade of Brazil in 1909, up to the present, 

 cassava has almost entirely been sent out in the form 

 of farine, but it has been found that it is more remuner- 

 ative, and safer, to export the root cut into small 

 round pieces and dried in the sun, so that hardly any 

 cassava is now shipped except that prepared in this 

 way. 



A New Means of Grafting. 



The Bulletin of the Bureau of Agricultural 

 Intelligence and of Plant Diseases, of the Interna- 

 tional Institute of Agriculture, December 1910, presents 

 an abstract of a paper which describes a means of 

 grafting, consisting simply in making oblique cuts in 

 the stork and scion, and fitting the oblique surtaces 

 closel}' together, the parts being kept in place by means 

 of a small piece of rubber tubing: the tubing should 

 cover the cut edges completely, so as to exclude air and 

 prevent drying. In addition to the fact of its giving 

 support, the advantages of rubber tubing used in this 

 v.ay are that it stretches and thus does not interfere 

 with the growth of the grafted plant, while the weather 

 causes it to rot, and drop away when it is no longer 

 required. 



The Stimulation of Plant Growth. 



In experiments on the growth and breathing of 

 plants, it has been known for some time that the action 

 of small quantities of poisonous substances, in relation 

 to these processes, is to increase the rate at which they 

 take place. In reference to the subject, the Experiment 

 Station Record, of the United States Department of 

 Agriculture, for February 1911 (Vol. XXIV, p. 1.38), 

 contains an abstract of a paper describing work which, 

 it is claimed, shows that such stimulation of plants 

 uuiy be brought about by means of nutritive substan- 

 ces, as well as by those which are poisonous. 



A matter of some interest is that, while phosjihates 

 had been shown to have little or no influence on the 

 respiration of living plants, they were found to possess 

 the power of greatly stimulating this in the case of 

 plants which hive been killed: as regards poisonous 

 substances, these were shown to have little effect on the 

 respiration of killed plants. 



A useful result of the work is to demonstrate that 

 the respiration of plants, as influenced by different sub- 

 stances, affords a means of finding out whether a given 

 stimulant is harmful to them, or otherwise. 



