DISEASES OF PLANTS. 651 



Species of Loranthus on rubber trees, F. T. Brooks (Agr. Bui. Fed. Malay 

 States, 3 {1914), ^o. 1, pp. 7-9).— The presence is reported of Loranthus on 

 rubber trees or estates in Negri Sembilan. 



Infection of wood by Coniophora, Trametes, and Polyporus, C. Wehmrr 

 {Ber. Deut. Bot. Gesell., 32 {191.',), No. 8, pp. 566-570).— Discussing briefly the 

 results of investigations previously reported (B. S. R., 32, p. S-15) and of others 

 more recently carried out, the author states that infection is assured only 

 when the fungus extends itself from mycelium already growing attached. 



Experiments of a preliminary character with T. radiciperda {P. annosus), 

 C. cerehella, P. vaporarius, and P. snlfureus on moistened fir wood kept in 

 flasks for eight weeks showed comparatively little development in case of 

 wood sterilized before infection and almost none in case of unsterilized wood, 

 while early and vigorous growth was observed on beer wort. The possible 

 bearings of these facts are discussed. 



The chemical action of the dry rot fungus on the substance of wood, C. 

 Wehmer {Ber. Deut. Bot. Gesell., 32 {191-i), No. 9, pp. 601-GOS).— The author 

 has extended his studies on the acidity apparent in connection with dry rot 

 fungi (E. S. R., 32. p. 150). Coniophora and Merulius were both tested as to 

 their effects on fir wood. 



It is stated that wood attacked by these fungi is no more acid than is sound 

 wood. It is held that the reddening of the litmus in this connection is prob- 

 ably not due to the presence of acid substances, but that it is a result of 

 colloidal action resulting from the acidity of the fungi. 



The toxicity to fungi of various oils and salts, particularly those used in 

 wood preservation, 0. J. Humphrey and Ruth M. Fleming ( U. 8. Dept. Agr. 

 Bui. 227 {1915), pp. 38, pis. 4).— The results are given of tests of 18 wood 

 preservatives against two wood-destroying fungi, Fomes annosus and F. 

 pinicola. 



The method employed was to determine the toxicity of the preservative on 

 the fungus grown in Petri dishes. While some inaccuracies were found in 

 this method, in general it was considered a satisfactory means of determining 

 the toxicity of the different compounds. 



In addition to a report on other investigations, the authors give a summary 

 of the results of the various investigators of this subject. It is claimed that 

 the chemical and physical composition of the media supporting the growth of 

 the fungus determines to a large extent its development. Temperature is also 

 an important factor in the growth of fungi, and the growth activities of fungi 

 are believed to bear a close relation to the resistance offered toward toxic 

 agents. 



The results of the experiments show wide variation in the amount of the 

 preservatives required per cubic foot of culture medium and also marked 

 differences in their effects on the two species of fungi experimented upon. 



A bibliography is appended. 



Toxicity of various wood preservatives, C. J. Humphrey and Ruth M, 

 Fleming {Jour. Indus, and Engin. Chem., 6 {191^), No. 2, pp. 128-131; 7 

 {1915), No. 8, pp. 652-658, figs. 4)- — A detailed report of the investigation 

 described in these papers is given above. 



Wallrothiella arceuthobii, J. R. Weir ( U. S. Dept. Agr., .Jour. Agr. Research, 

 4 {1915), No. 4, pp. 369-378, pis. 2). — This fungus, which is parasitic on the 

 false mistletoes, was first reported in New York and later in IMichigan (E. S. R., 

 13, p. 2.59). The author of the present article reports its frequent occurrence 

 on the false mistletoe in Idaho and Montana. In addition to the species 

 Razou/niofskya pusilla, the host plant on which it was first discovered, the 



