Vol. XII. No. 2S<3. 



THE AGRICULTURAL NEWS. 



123 



A^irgin OorcU, tlie fallen leaves appe.ir to decay but slowly, and 

 inscri])tions on such may be deciphered long after they 

 have been shed and dried. 



'The seeds contain a pitcliy icsin, which is used for 

 caulking the seams of boats, for which purpose it is said to 

 be the equal of asphalt. This rosin is recovered in an 

 ingenious manner. The seeds are sot in an ordinary Dutch 

 .-stove, or "coal pot" and set alight, Imrning readily of course. 

 The melted resin flows down through the grate, and is 

 •;ollected in the ash chamber below.' 



With a view to obtaining further iuformalion on the 

 .subject and fre.sh specimens, the Curator of the Botanic 

 Station of the Virgin Islands was communicated wit-h The 

 botanical name of the tree was not known locally, though 

 several specimens of the tree were stated to occur in the 

 islands, and the properties of the seeds were also familiar. 



Eventually, specimens of the leaves and fruit of the tree 

 •were received from the \'irgin Lslands and forwarded, together 

 with the information given above, to the Royal Botanic 

 ^ iardens, Kew, for identification. 



Recently a communication from the .Assistant Director 

 states that the tree proves to be dnsia rost'i, Jacq. (N. <). 

 'lUttiferae). No sample either of the seeds or of the resin was 

 found in the Kew collections, ami accordingly specimens will be 

 forwarded in due course from this Department for inclus- 

 ion in the Kew museum. 



SOIL-SICKNESS AND PARTIAL 

 STERILIZATION. 



The recent endeavours to deal with cases of soil-sickness 

 by means of partial sterilization have arisen from the 

 di-scovery, some few years ago, that this treatment increases 

 bacterial activity in the soil mainly through the reduction of 

 the number of larger competing organisms (protozoa). The 

 change in the flora of the soil thus brought about, increases 

 the production of plant nutrients, and hence influences 

 favourably the growth of cultivated crops. An interesting 

 account of this side of the subject will be found in the 

 following references: Ai/rindfiiiul Xi'ics, Vols. IX, pp. .33 

 and 107; .\1, pp 131 and 106, where an account is given of 

 the original Rothamsted work, and a description included of 

 curious sterilization practices in India. 



The present article is written with special reference to 

 a paper by Russell and I'etherbridge, which appears in the 

 Journid nf the Board uf Agrioiilare, for .lanuary 1913. 

 This paper, which is entitled 'Partial Sterilization of Soil for 

 Glass-hou.se Work', describes the results of experiments in 

 continuation of previous ones, to be found in the Experiment 

 Station Record, Vols. XXII, p. 121; XXVI, p. SI. 5, XXVII, 

 pp. 6'20 and 621. Reference to this literature will show that 

 during the last year or two, attention has been given to the 

 matter of partial soil sterilization mainly from the pathological 

 aspect. The healthy or unhealthy nature of the soil, and not 

 merely its supply of plant nutrients, has been the central 

 object of investigation. 



It has been established in the United States, the 

 Transvaal, as well as in England, that the so-called sick soils 

 can, in many instances, be rendered healthy by subjecting 

 them to a temperature of 100°F. to 200° F. or by means of the 

 application of antiseptics. The late.st information on the 

 subject, contained in the paper by Russell and Petherbridge, 

 referred to above, deals mainly with the application of anti- 

 septics in practical horticulture Sick soils to tomatos, 

 cucumbers, vines, ferns, peas and tobacco receiveii .special 

 investigation. 



It might be pointed out at once that by a touiat?! 

 sick soil is meant a soil that induces in tomato plants 

 grown in it, a pathological or diseased condition of so 

 serious a nature that their cultivation ceases to be profit- 

 able. It is of the greatest importance to bear in mind 

 that it is not the crop that causes sickness of the soil, but 

 the soil that causes sickness of crop There are some virgin 

 soils, for instance, in which vines cannot be grown without 

 artificial treatment. That treatment is partial sterilization. 

 In garden or nursery work, heating of the soil is not likely 

 to be so convenient as the application of antiseptics; for 

 glasshouse or pot- work, however, the heating method can bi- 

 employed with commercial success. Of the common antiaci: 

 tics, carbolic ncid, calcium sulphide and formaldehyde have 

 given good results — even better than those results obtained 

 previously by using toluol. The selection of an anti'septic i.s 

 controlled by several factors.for example, efficiency, original 

 cost and expense of transport, and has to be settled by consider- 

 ing the conditions of each particular case. But the fact remaias 

 that their use cures the sickness, kills the disease organism.^ 

 in the soil, and incidentally increases the supply of plant 

 food. What the different sicknesses really are is not at pre- 

 sent definitely known; it may be that toxic or poisonous sub- 

 stances (to the particular crop ati'eoted) occur in the soil as 

 the excretions of certain fungi and bacteria. Sometimes the 

 sickness can be, in part, attributed to the presence of 'damp- 

 ing of}" fungi like the widely spread Pythiumand Rhizoctonia. 

 Future investigations will in all probability reveal the e.Kact 

 causes in every case. 



In concluding these considerations, it may be remarked 

 that the possibility of the local application of partial steriliza- 

 tion to certain West Indian soils .seems to be suggestive, and 

 the subject will also bear consideration in connexion with 

 specific root diseases. A remedy for these may lie in the 

 partial sterilization of the soil. 



Animal Nutrition; Recent Results.— Arm.sby 

 and Fries have shown that there is an increase of 

 metabolism (building up and breaking down of food in 

 the body) in cattle when they are in a standing, az 

 compared with a lying, position. The increased emission 

 of heat during the standing periods is accompanied by 

 a corresponding elimination of both carbon dioxide and 

 water. Working on the tolerance for sugar in the pig, 

 Carlson and Drennan have found that slow but fatal 

 diabetes occurs in the pig after removal of the pancreaa. 

 The pig was found to have a lower tolerance for dex- 

 trose than any species so far studied, that is it becomes 

 glycosuric (secretes glycogen or animal starch) when quite 

 small amounts of sugar are given by the mouth. Perhaps 

 the most interesting of recent work is that of R,eale oil 

 carbon metabolism. This investigator estimated by a wet 

 oxidation process (with chromic and sulphuric acid.s) the 

 amount of carbon in urine It was found that only about 

 half the carbon in the urine e.xists in the form of urea It 

 was also discovered that a part of the carbon is readily oxidized 

 to carbon dioxide in the presence of hydrogen peroxiile 

 when manganese peroxide is used as a catalyst. This is 

 <lesignated by the author 'labile carbon, whereas the carboft 

 which is not so oxidized is called 'stable carbon'. Intere.st- 

 ing results have also lately been obtained by Moldoven oa 

 the method of action of (juinine on trypanosomes. Separa- 

 tion of droplets of lipoid character occurs, producing a change 

 in the osmotic relationship of the protoplasm to its .sur- 

 roundings. Final cause of death is stoppage of oxygea 

 respiration. (From the Journal, of the Ckcinical Society, for 

 February 1913.) 



