658 PROCEEDINGS OF SECTION K. 



a great deal of work in experimenting with the foregoing elements 

 and with lithium caesium and uranium, find that they stimulate 

 the growth of a number of plants both in the field and in pots. 

 Titanium has also been found to increase the yield of crops. C. E. 

 Wait has found titanium in the ash of every plant which he has 

 examined, and Annett states that the colour of the black cotton 

 soil of India is due to the presence of a titaniferous mineral. I 

 have found titanium to be present in soils of the black-soil plains 

 in the north-west of New South Wales, but cannot assert that this 

 is the cause of their colour since other soils from the same locality, 

 and derived from the same minerals, are red or chocolate in colour, 

 and also contain titanium. The addition of flowers of sulphur has 

 also been found to improve the yield of many crops. Copper is 

 also stated by some writers to increase plant growth when present 

 in small quantities, but by others t^t^e injurious. Boron appears 

 to be very widely distribvited in the plant world, and the proof of 

 its presence as a natural constituent of grapes and of wines is of 

 considerable economic interest. At the rate of ^-gramme per 

 square meter, it has been found by Agulhan to increase enor- 

 mously the yield of wheat, maize, rape, and turnips. 



The literature with regard to manganese, its occurrence in 

 plants, and the action of minute quantities, is voluminous. In 

 minute quantities it appears to be beneficial, in larger quantities 

 toxic, and its toxicity appears to increase with its stage of oxida- 

 tion. 



Other substances that may be mentioned in this connexion are 

 vanadium, chromium, nickel, barium, zinc, mercury, didymium, 

 and glvxcinum. 



For the most part these substances are plant poisons, but quite 

 remarkable benefits have' been obtained by their application in very 

 small quantities. 



A bibliography prepared by Mr. L. A. Musso, of the chemist's 

 branch, Department of Agriculture, New South Wales, appears 

 as an appendix to Science Bulletin No. 9, published by the N.S.W. 

 Department of Agriculture, and may be found useful to those who 

 wish to look up the literature of the subject. ^ It may very well be 

 that some extremely important discovery may be made as the result 

 of the study of these catalytic fertilizers, one that may throw some 

 liglit on the question of plant assimilation. Among the most 

 striking results obtained to date appears to be the very remark- 

 able effects produced by some of these metallic salts upon moulds, 

 the effect, for example, of zinc upon the development of Aspergillus 

 niger, ten times the quantity of this mould being produced in solu- 

 tions containing 1 in 50,000 of zinc. 



' An excellent resumi of thi.^ subject is also published by M. Cercelct {Edvue de Viticulwre 

 Tome 38, No. 9^1, p. 381). 



