February 22, 19 12] 



NATURE 



567 



of energy, especially in radiation, with the author's usual 

 ability, and the same may be said of the fifth paper, by 

 the same sliilful experimenter, on the deviations of the 

 oscillations of a viscous solid from the isochronous law. 

 Mr. J. P. Dalton gives a careful digest of the accuracy 

 attainable with a modified form of Att wood's machine, 

 whilst Mr. J. B. Ritchie further extends previous researches 

 by Prof. Peddle on the dissipation of energy and other 

 effects observed in torsional oscillation. The last of this 

 series is an account of interesting experiments on wave 

 impact on engineering structures, carried out by Prof. 

 A. H. Gibson and Mr. W. N. Elgood, resulting' in the 

 conclusion that the effective internal pressure due to wave 

 impact cannot exceed that exerted by wave impact on the 

 face of a breakwater, and suggesting the provision of 

 drains opening on the sheltered face. 



The section devoted to chemistry contains a critical 

 account of a new series of methylated sugars recently 

 obtained in the Purdie Research Laboratory at St. 

 Andrews by Prof. Irvine. The extended application of 

 these researches is reviewed in an excellent paper bv Mr. 

 C. R. Young, whilst Mr. W. S. Denham ably treats of 

 new methods in the preparation of anhydrides of organic 

 acids, and Mr. R. C. \^■allace deals with the relation- 

 ships of indium and thallium. These researches give an 

 indication of the importance and variety of the work 

 recently carried out in this department. Under the section 

 of natural history and medicine, Prof. Mcintosh gives a 

 brief history of the chair of natural history at St. 

 Andrews, and Prof. D'Arcy Thompson reprints his presi- 

 dential address to the British Association, entitled 

 " Magnalia Naturae: or the Greater Problems of Biology." 

 The next paper is by Prof. E. E. Prince, dealing with the 

 pioneer work in scientific fishery investigations at St. 

 Andrews, and makes mention of many workers, now 

 scattered in diverse regions, who have extended our know- 

 ledge of the department in a noteworthy manner, and by 

 none more than the writer of the article. The last is a 

 medical contribution on the important subject of the 

 toxicity of local anaesthetics, by Prof. C. S. Marshall, who 

 carried out a series of careful experiments with no fewer 

 than eight drugs. 



N'o zoological researches are included in the volume, 

 since its scope was not understood until too late for the 

 insertion of the able contributions of such well-known 

 investigators as Dr. H. C. Williamson, Dr. H. M. Kyle, 

 Dr. Wm. Nicoll, and many others whose names appear in 

 the list of publications emanating from the Gatty Marine 

 Laboratory. 



THE CONTROL OF INSECT PESTS IN 

 CANADA. 



A T the meeting of the Manchester Literary and Philo- 

 "^ sophical Society on January 9, Dr. C. Gordon 

 Hewitt, Dominion entomologist, gave an account of the 

 ravages of insect pests in Canada, and the means taken 

 by the Dominion Government to combat them. The 

 annual opening up of vast tracts of country, previously 

 wild, destroys the balance of nature, and swarms of 

 insects, finding fresh stores available, devastate the new 

 growths. Some of these insects are of native origin, but 

 are more frequently introduced. Thus the Hessian flv, 

 Mayctiola destructor. Say, appeared in 1816 ; the wheat 

 midge, Diplosis tritici, Kirby, in 1828 ; the chinch bug, 

 lUissus Iciicopterus, Say, in 1866 ; and the Colorado 

 potato-beetle, Leptinotarsa decemUneata, Say, in 1870. 

 The larch sawfly, Lygacouewatus erichsouii, Hartig, 

 reached Canada in 1882, and in a few years destroyed the 

 mature larches over practically the whole of eastern 

 Canada. The pear-leaf blister-mite, Eriophyes pyri, 

 Nalepa, was first reported from Nova Scotia about 1887, 

 and has since spread across Canada from the .Atlantic to 

 the Pacific. 



Other pests referred to included the clover-root borer, 

 Hylesinus trifolii, Muller ; the warble-fly ; the apple fruit- 

 miner, Argyresthia conjugella, Z. ; the apple maggot, 

 Rhagoletis potiionella, Walsh ; and the San Jos^ scale, 

 Aspidiotus peruiciosus, Comst. It was found necessary 

 to pass the San Jos6 Scale Act, prohibiting the importation 

 of trees and nurserv stock from countries in which the 



NO. 2208, VOL. 88] 



scale was known to exist ; in 1901 the restriction was 

 removed, but infected plants were fumigated bv prussic 

 acid before admission. The brown-tail moth, Euproctis 

 clirysorrhoea, L., has now reached Canada, and is attack- 

 mg oak, elm, and maple, in addition to fruit trees. Con- 

 trary to expectations, the severe winters of Canada do not 

 prove to be so fatal to the larvae ; experience has shown 

 that some 30 per cent, survive after being frozen for two 

 months in a block of ice. Attention is therefore being 

 given to the parasites of this species ; also the severely 

 infested trees are sprayed to kill the young larvce. 



Dr. Hewitt gave an account of the precautionary 

 measures taken and of legislation in the Dominion, and 

 of the history of the Entomological Department there. 

 Educational work is undertaken, and agriculturists and 

 associations addressed on the means of prevention and 

 control of outbreaks. At Ontario Agricultural College, 

 and in other provinces, men are trained to act as 

 assistants and inspectors in this branch. 



• EXTFA^XAL " DEGREES AT THE UNIVERSITY 

 OF LONDON. 



CIR WILLIAM RAMS.AY'S letter to Nature on the 

 "^ value of the " external " degrees of the University 

 of London, published on February i (vol. Ixxxviii., p. 445), 

 has given rise to a number of letters upon the subject. 

 .\s several correspondents traverse the same ground, and 

 limitations of space will not permit us to publish the letters 

 in full, we subjoin a summary of the chief points raised. 



Dr. A. D. Waller, F.R.S., thinks that no useful pur- 

 pose would be served by any discussion of the particular 

 case cited by Sir William Ramsay, where it is suggested 

 an injustice has been done to a late student of University 

 College, and proceeds to consider the principle involved. 

 He urges that the great desideratum as regards the 

 superior degrees of the University — "internal" as. well. as 

 " external " — is not the abolition of the " external " 

 degree, but publicity during examination of both kinds. 

 A candidate presenting a doctoral thesis to the University 

 is, says Dr. Waller, in the position of an investigator 

 presenting a . communication to a learned society, and 

 ought to be called upon, or permitted, to expound and 

 uphold his thesis by. speech and by demonstration in the 

 presence of the University. The " external " examinations 

 ought not, he maintains, to be abolished, for they have 

 been, and are, of far-reaching value as affording a guide 

 to study and a standard of. excellence throughout the 

 Empire. 



Prof. T. Johnson, of the . Royal College of Science, 

 Dublin, directs attention to the fact that the University of 

 London was founded, in part, for students whom circum- 

 stances prevent from attendance at the London courses of 

 instruction, and argues against the abolition of the 

 " external " side in the University. He contends that the 

 agitation for the conversion of the examining into a. teach- 

 ing university had its origin largely in the unpublished 

 desire to safeguard certain vested interests. It was no 

 uncommon thing in the old days, he says, for a professor 

 in a London college to find his salary reduced owing to 

 loss of fees caused bv his replacement, at the end of his 

 term of office as an ' examiner, by a provincial or other 

 examiner. " This ' anomaly ' or ' injustice ' was removed 

 by the creation of the University's teaching side and intern 

 examinerships." 



Mr. W. J. Oakes, of the Oakes Institute. Walton, Liver- 

 pool, emphasises the similarity in the roquirements. so far 

 as the arts courses are concerned, for " internal " and 

 '• (Xternal " degrees, and attaches groat importance to the 

 fact that " external " candidates for science degrees must 

 provide suitablv attested evidence of practical training in 

 a laboratory. He points out the comparatively small pro- 

 vision in provincial centres of scholarships to enable yoijng 

 men and women to attend day courses at local universities. 

 He asks. " What are the young men who come from homes 

 where the income is less than 200/. a year to do? " If 

 no other case could be made out for the " external " 

 degree than that of the young men who cannot possibly 

 attend the day classes of a university, this would. Mr. 

 Oakes says, outweigh .ill the arguments which can be 

 advanced against it. 



