•Vol,. XII. No. 285. 



THE AGRICULTURAL NEWS. 



105 



Since the separation of insoluble matter was 



equally complete in every case it follows that the 



nitrogen content of rubbers is only a very rough guide 



•as to the amount of insoluble matter that they contain. 



The samples were then vulcanized with sulphur 

 under pressure and analysed and also tested physically. 

 It was found that Ceara and Rambong rubbers behave 

 in the same manner as Hevea on removal of the insolu- 

 ble constituent, the effect being to reduce the percen- 

 tage of combined sulphur, the lesulting vulcanized 

 rubbers being much undercured and very weak, whilst 

 the untreated lubbers under the same conditions of 

 vulcanization are fully cured or even overcured. Simi- 

 larly the effect of additional insoluble matter is to 

 increase the proportion of combined sulphur. 



By calculating the percentnge of nitrogen remain- 

 ing in the rubber free from insoluble matter, on the 

 nitrogen originally present, it was concluded that the 

 insoluble matter in rubber plays the part of a sulphur 

 carrier and vulcanizing agent independently of the 

 proportion of the nitrogenous substance or substances 

 which it contains. 



Streptothrix in the Soil. 



These micro organisms have been found to be 



instrumental in fixing the nitrogen of fertilizers and 

 soils, thereby diminishing the loss from denitrification. 

 According to the Experiment Station Record fo< 

 November 1912, results have shown that Steptothri.v 

 compose from 20 to 30 per cent, of the micro-organismf 

 in loam soils, from ^ to 1-5 per cent, in clay soils, and 

 from 7 to 10 per cent, in sands. Fallow soils contained 

 larger numbers than cultivated soils. Streptothrix are 

 able to decompose peptone, blood, bone meal, and straw, 

 splitting otT large quantities of ammonia which is 

 retained in the soil for the use of plants. 



The organisms jiroduced no nitrification nor was 

 there any assimilation of free nitrogen, but the presence 

 of these organisms did not diminish the assimilative 

 capacity of Azotobacter. 



It is stated that Streptothrix aid in the production 

 of nodules on the roots of Papillionaceous plants. 



The organisms are also abundant on roots of 

 Asjiidium, Quercus, Ulmus, Gramineae and on decaying 

 plant di'bris. 



The Adulteration of Jams. 



In view of the industrial importance of preserve- 

 making in certain parts of the West Indies, and of the 

 large consumption of imported jams in these Colonies, 

 considerable interest attaches to a paper on the above 

 subject which appears in the Journal of the Royal 

 Society of Arts for February 21, 1913. 



In this it is stated that although many jam 

 manufacturers, by using illusive labels, generally keep 

 within legal limits, yet the adulteration or so-called 

 'improvement' of jams by the addition of the juice of 

 cheaper fruit of another kind is widespread and 

 extremely profitable, in spite of occasional fines, to the 

 manufacturers concerned. Lurid accounts of the 

 employment ot turnips, carrots, vegetable marrow, or 

 of the celebrated pip-making machine are not to be 

 considered seriously. The mainstay of adulteration by 

 intermixture is the apple, whilst lemons, gooseberries 

 and even rhubarb are used in some cases. ]\Iarmalade 

 is often deprived of peel to supply the re(iuiremcnts of 

 essence or candied-peel makers. In the case of straw- 

 berry jam the addition of gooseberry juice appears to 

 be necessary to supply the slitfening principle (pectin) 

 which is greatly lacking in the strawberry fruit. 



In considering the detection of impurities it is 

 stated that fragments of extraneous fruits can be 

 detected by simple microscopical methods preferably 

 with the use of polarized light. Lemon and orange 

 preserves, for instance, contain curious contorted cells 

 very different from any structure in English fruits. 

 The detection of juices, however, recjuires the applica- 

 tion of a method based on a knowledge of colloids. 

 The method is known as the lead iodide process. 'J"he 

 principle on which it rests is the formation in different 

 juices of specific aggregates which are photograjihed 

 <inder the microscope before crystallization sets in. 



New Varieties of Alfalfa. 



Several attempts have been made in the past to 

 establish alfalfa as a fodder crop in the West Indies. 

 The general experience has been, however, that the 

 crop flourishes during the first year but eventually 

 .loses its vigour and often succumbs to what appears to 

 be a root disease. Several strains of seed have been 

 experimented with: seed raised in the W'est Indies, and 

 seed obtained from Arabia through the courtesy of the 

 United States Department of Agriculture. In one 

 island where this African seed was tried under estate 

 conditions, there seemed to be some possibility of its 

 possessing the reijuisite characteristics, and the matter 

 calls for further consideration in connexion with infor- 

 mation recently presented in BiUletin No. .'J.V of tfce 

 Bureau of Plant Industry of the United States 

 Department of Agrieulture, 



This Bulletin describes the breeding (including 

 methods of cross-pollination) and the characteristics of 

 new varieties of alfalfa possessing definite under- 

 ground stems. The biological significance of these 

 rhizomes is, of course, resistance to climatic extremes. 

 Many of the varieties found lately in Northern 

 Africa bear rhizomes which may travel several feet 

 before coming to the surface. During the under- 

 ground development, branching takes place to a greater 

 extent than has been observed previously in other forms, 

 but the roots on these alfalfas are not well developed, 

 at least during the earlier stages of growth. The 

 varieties grow in exceedingly dry sandy soil under the 

 intense heat and drought of African summers, and it is 

 remarked that a similar growth would be a welcome 

 sight in the semi-arid regions of the United States. 

 It does not seem improbable that in this newly consid- 

 ered feature of alfalfa may lie the secret of successful 

 selection and cultivation of the crop in the West Indies. 



