46 



7 and 22 per cent., and the content of CH./) in the extracts 

 between 13.5 and 14.7 per cent. A qualitative test for "tuba- 

 toxin," devised by Dr. Durham, is outlined. 



The amounts of the non-toxic constituents vary widely in 

 different consignments. They seem to have some value as 

 emulsifying- and wetting- ag-ents. As the root, however, arrives 

 in this country in a dry state, in which the constituents have 

 probably coalesced, the use of foreig-n emulsifying and wetting 

 reagents is necessary, and for maximum efficiency the use of 

 organic solvents for preparing highly dispersed suspensoids 

 appears advisable. 



FUNGUS PESTS. 



XLV. William B. Bkieklky. "Oji Mutation of Species." 

 British Medical journal, 1922, Oct. 21st. 



The main genetic bases of ''higher organisms" are discussed 

 in relation to the concept of mutation and then in relation to 

 hereditary changes in the protozoa, fungi and bacteria. The 

 concepts of mutation held by microbiologists are considered, and 

 it is shown that they cannot be equated with those applied to 

 "higher organisms." Micro-organisms have not yet been found 

 susceptible to factorial analysis and cvtological information 

 regarding the genetic structure and behaviour of their hereditary 

 mechanisms is not available. In the protozoa and fungi, and 

 probably in the bacteria, there is the possibility of the origin of 

 apparently new forms in the normal developmental processes, and 

 it is sug-gested that "mutations" are due to the selecti\'e isolation 

 of such forms. 



XLVI. William B. Brierley. ''Some Aspects of Vegetable 

 Pathology in Relation to Human Disease." British 

 Medical journal, 1922, Nov. 18th. 



The need for extreme caution in making comparison of animal 

 and plant diseases is emphasised, and the lines along which animal 

 and plant pathologists may work in common are suggested. 

 These are mainly comparative morphological, physiological and 

 life history studies of the several pathogens in relation to such 

 problems as systematy, infection, immunity and susceptibility, 

 mutation and other genetic aspects, epidemiology, technique, etc. 

 A plea is made for the definite recognition of a science of medical 

 mycology with adequate teaching and research opportunities. 



XLVII. William B. Brierley. ''Comparative Pathology of 

 Plants and Animals." British Medical Journal, 

 1922. 



The idea of disease accepted in general pathology is that of the 

 invasion of a defensive host by an active parasite, a see-saw 

 balance in which there is an inverse relationship between the 

 health and vigour of the host and the incidence and virulence of 

 the disease. This concept is criticised and evidence given that in 

 diseases of plants it is not necessarily true. The data at present 

 do not allow of such a generalisation and each particular disease 

 complex must be considered separately. The disease complex is 



