January 6, 191 6] 



NATURE 



513 



The report by Mr. Keele on the clays of Quebec (3) 

 shows that Canada recognises the importance of 

 a definite knowledge of its clay resources. In 

 the preface Mr. Keele says : " Chemical analyses 

 are of little value to him {i.e., the clay-worker), as 

 practically no information regarding- the behaviour 

 of clays can be derived from such analyses." This 

 might be true if the statement refers to some clay- 

 workers ; but it does not require a Gaboriau's 

 Lecoq to deduce a very great deal of important 

 practical information from the analysis of a clay, 

 information, too, which could be otherwise 

 gleaned only after painful processes of trial and 

 failure. The methods of collecting the so-called 

 practical data are largely those followed in the 

 prepara:tion of numerous other reports published 

 further south. This is good so far as it goes, but 

 we must remember that some of the best of these 

 reports were pioneers in this department of clay 

 literature, and have served a very useful purpose. 

 There are many important properties of clays 

 which the progressive worker ought to know 

 which might advantageously have been included. 

 New knowledge, new requirements. Of course, 

 Mr. Keele 's report is mainly of local interest, and 

 without a knowledge of the particular district 

 covered by the memoir it can be said that the 

 present report compares very favourably with the 

 best of those made for other localities. 



J. W. Meli.or. 



SCIENTIFIC STUDIES OF SJVINE FEVER.^ 

 'T^HE committee appointed by the Board of 

 -I- Agriculture and Fisheries to inquire into 

 swine fever has issued its final report, which con- 

 tains conclusions of far-reaching importance, and 

 since the main conclusions are based on the re- 

 sults of experimental investigation carried out 

 on the recommendation of the committee by one 

 of its members, Sir Stewart Stockman, who is 

 also the Chief Veterinary Officer of the Board, 

 the report would appear to portend an early 

 radical change in the campaign against the 

 disease. 



The causal agent of swine fever is a living 

 organism which is beyond the range of micro- 

 scopic visibility, and will pass, with fluid contain- 

 ing it, through the pores of the finest bacterial 

 filter. No method of cultivating it artificially has 

 yet been discovered. 



Amongst its conclusions, the committee makes 

 the following statements : — That the manure of 

 pigs suffering from swine fever is infective, and 

 that a period of fourteen days may be regarded as 

 sufficient to bring about the disinfection of in- 

 fective manure through natural causes ; (one 

 member of the committee, however, Prof. Pen- 

 berthy, considers that the experiments on which 

 the latter view is based are not conclusive, and 

 that further experimentation on the point should 

 be undertaken before being accepted as a basis 



1 Final Report of the Departmental Committee appointed hy the Board 

 of Agriculture and Fisherie* to inquire into Swine Fever. Part iv. Final 

 Report,^ Minutes of Evidence and Appendix. Cd. 8045. Price So'. Can 

 be obtained direct from Mefsrs. Wynian and Sons or through any bookseller. 



NO. 2410, VOL. 96] 



for administrative measures); that rats are not, 

 as has been suggested, pathological carriers of 

 swir'ie fever, and that all the available evidence 

 suggests that swine fever is not disseminated by 

 external parasites, such as lice and fleas; that 

 while persons, vehicles, and animals may carry 

 infective material mechanically, the evidence leads 

 to the conclusion that all wide dissemination of 

 the disease is due to the movement of infectivtf' 

 pigs ; that a pig may become infective in three 

 days after contracting infection, and before it has 

 actually exhibited clinical symptoms of the 

 disease, and may remain infective for a consider- 

 able period, the extent of which has not been 

 fully ascertained ; and that there would appear to 

 be cases in which healthy pigs, which have not 

 been visibly affected by swine fever and on post- 

 mortem examination show no evidence of having 

 suffered from swine fever, yet are infective, 

 and continue to be so for a considerable 

 time. 



On the question of serum treatment and vac- 

 cination as methods of combating swine fever, 

 the committee reports that the serum of a hyper- 

 immune pig, if injected into other pigs, will pro- 

 tect them for a short time against swine fever if 

 they are free from infection at the time of treat- 

 ment, but it is disappointing in the case of young 

 sucking pigs. It has no curative effect. This 

 short period of immunity can be converted into 

 a prolonged immunity if the pigs treated with 

 serum are allowed to tome into contact with 

 infection, i.e., by what may be termed "natural 

 vaccination." "Artificial vaccination" may also 

 be carried out. It consists of the simultaneous 

 application of serum injection with an infection 

 produced by the administration of virus by feeding 

 or by inoculation, but the process is attended by 

 greater risks of producing severe forms of swine 

 fever than "natural vaccination." 



The committee is of opinion that the continual 

 prevalence of swine fever appears to be due 

 principally to its highly contagious character and 

 the difficulty of its recognition by the pig owner 

 in its early stages and in its milder forms ; and the 

 members consider that the extirpation of the dis- 

 ease is practicable only by such drastic measures 

 of slaughter as would involve a prohibitive outlay, 

 and by such severe restrictions on movement as 

 would be fatal to the industry of pig-keeping. 

 New preventive methods, however, may bring 

 about a condition more favourable to the prospect 

 of eradicating the disease. 



Recommendations. — In view of all the evidence 

 laid before them, the committee recommends that 

 the attempt to extirpate the disease by general 

 slaughter should be abandoned for the present, 

 and that the immediate object of future policy 

 should be to reduce the mortality from the disease 

 by the use of protective serum as soon as pos- 

 sible in infected herds. The production of im- 

 mune herds by " artificial vaccination " should be 

 undertaken under suitable conditions. To con- 

 trol the spread of the disease, isolation of infected- 

 premises should be maintained, but restrictions 



