September 29, 1923] 



NA TURE 



487 



energetic direction of Surgeon-Commander D. H. C. 

 Given. In the words of Mr. Marshall, " Both in 

 Hayling and Gosport the mosquito nuisance has 

 already decreased by an almost unbelievable extent." 

 This satisfactory result is largely due to the pre- 

 liminary biological investigations. These showed, 

 first, that practically the whole of the nuisance was 

 due to one particular species, Ochlerotatus detritus. 

 Not only was it found that this species far out- 

 numbered all the others put together (in the pro- 

 portion, it is said, of not less than looo to i), but also 

 it was found that the domestic Ciilex pipiens, present 

 in fair numbers, was not addicted to sucking human 

 blood. In the second place, the very important 

 discovery was made that O. detritus will only breed in 

 more or "less salt water which is allowed to stagnate. 

 The control of this species is therefore largely a matter 

 of ensuring that no salt water is allowed to become 

 cut off from tidal action, and by united effort this can 

 l.c done in any of the coastal towns where this 

 ]iarticular species is the chief offender against the 

 comfort of the inhabitants. Such work must, how- 

 ever, cover a considerable area, for O. detritus has 

 been found to spread at least four miles from its 

 breeding-grounds. The experiences at Hayling should 

 prove valuable in any attempts which are made in 

 the control of our second salt-marsh species, Ochlero- 

 tatus caspius, which is now known to be the chief 

 cause of the mosquito nuisance in the London area, 

 as well as at some East Coast resorts. In this case, 

 however, the problem is complicated by two 

 difficulties : in the first place, O. caspius does not 

 breed exclusively in salt water, and, secondly, its range 

 of flight appears to be much greater than that of 

 O. detritus. It can scarcely be doubted, however, 

 that a much closer study of the distribution and 

 biology of O. caspius would reveal facts of which 

 practical use could be made in reducing its numbers. 

 The prime importance of such biological work has 

 been well illustrated at Hayling. 



Cainozoic and Recent Austral Rhvnchonel- 

 LiDS. — In Nature, vol. no, p. 262, 1922, the fate 

 that has overtaken the genera Terebratula and 

 Rhynchonella, mostly under the penetrating eye of 

 Mr.' S. S. Buckman, was mournfully recorded. Mr. 

 h\ Chapman (Proc. Roy. Soc. Victoria, vol. 35, p. 175, 

 1923) now finds that Hutton's Rhynchonella squamosa 

 must become the genotype of a new genus (here 

 called by a misprint " sp. nov."), which he names 

 Tegulorhynchia. A critical description, with figures 

 and a bibliography, is given of the Cainozoic and 

 recent rhynchonellids of the austral region. 



Hard X-ray Tubes. — In the issue of Die Wissen- 

 schaften for September 7, Prof. Knipping, of Heidel- 

 berg, gives a summary of his work on the cause of 

 the inability to transmit electric current which is 

 found in X-ray tubes after they have been in use for 

 some time, even when the pressure of the residual gas 

 in them is raised to o-oi mm. of mercury by the 

 regenerative arrangement with which they are 

 generally provided. He finds that the effect is clue 

 to the absence of positive nuclei of hydrogen atoms 



liich are necessary to render any gas at low pressure 



inducting. In their absence a gas at the above 



pressure behaves towards the passage of electricity 



like a perfect vacuum, and the author speaks of such 



s;as as a pseudo high vacuum. In normal circum- 



inces the hydrogen nuclei are provided by the 

 moisture which is condensed on the walls of vacuum 

 lubes, and continued use of the tubes exhausts this 

 supply. Prof. Knipping is continuing his investiga- 

 tion, and points out that the present theory of the 

 '"Tiission of electrons from heated bodies requires 



NO. 2813, VOL. 112] 



modification to include the effect of the surrounding 

 medium. 



CoLLoiDAE Properties of Rice Starch. — It is 

 well known that the granules of starches vary not 

 only in their appearance according to their origin but 

 also in their properties ; thus sago, tapioca, and 

 cassava starches yield more glutinous sols than others. 

 This difference is well marked between the common 

 and glutinous rice starches, and IMessrs. T. Tadokoro 

 and S. Sato have made this the subject of an interest- 

 ing paper in the Journal of the College of Agriculture, 

 Hokkaido Imperial University (1923, vol. 13, p. 1-65). 

 These authors show that there is a difference in the 

 behaviour of the two kinds of granules towards 

 iodine, and both in suspension and in dilution the 

 affinity of glutinous starch for iodine was less than 

 that of ordinary starch. Coagulation of the solutions 

 by the addition of alcoholic hydrochloric acid or by 

 solutions of metallic salts was obtained more readily 

 with ordinary starch. The colloidal properties as 

 shown by the hydrating power, water retention, 

 viscosity and protective action (gold value) of the 

 strong solutions was greater in the case of glutinous 

 starch, thus indicating the greater dispersion of this 

 substance in solution. In the formation of a jelly 

 by the addition of tannin solution, a greater quantity 

 of the reagent was required for the glutinous starch, 

 and the ultramicroscopic appearance of the gel re- 

 sembled a network instead of a foam as shown by 

 the gel of ordinary starch. Further differences were 

 shown by the two varieties of starch with regard to 

 the decomposition of the blue iodine compounds by 

 X-rays and various reagents, and the adsorbent 

 power of charcoals derived from the starches by 

 ignition. In spite of the many differences in colloidal 

 behaviour of these two starches, there was no notice- 

 able variation in their ordinary chemical properties. 

 The observed differences are attributed to a different 

 degree of polymerisation between the starches. 



Liquid Fuels in Australia. — The Australian 

 Commonwealth Institute of Science and Industry 

 has issued a bulletin (No. 24) compiled by R. E. 

 Thwaites on " The Production of Liquid Fuels from 

 Oil Shale, and Coal in Australia." The main part 

 of the bulletin is occupied with a survey of mineral 

 oil supply viewed as a world problem. It gives an 

 interesting and comprehensive review, both technical 

 and economic, together with speculations as to the 

 future sources of liquid fuel. The problem is then 

 analysed as it bears upon Australia itself. There 

 the conditions seem to resemble those of Western 

 Europe. Proved deposits of niineral oil are scanty 

 or non-existent. Home produced liquid fuel will 

 have to be derived from oil shales, lignites, and 

 bituminous coal, of which considerable deposits are 

 now exploited or known. The oil shales though 

 rich are limited in quantity and an existing industry 

 engaged in their distillation is at a standstill, rendered 

 unremunerative for the moment by high working 

 costs. The proved deposits of such shales would 

 not, however, furnish Australian requirements at 

 present rates of consumption for more than ten 

 years. The supply in the future will have to be 

 based on coal and brown coal both occurring abund- 

 antly. The existing towns' gas industry, carbonising 

 coal at high temperatures, already makes a useful 

 contribution of liquid fuel. The author looks for 

 greater production in the future from this source 

 and from developments of carbonisation at low 

 temperatures. The technical and economic problems 

 involved are recognised and a plea is advanced for the 

 institution of a fuel research laboratory to explore the 

 subject with special reference to Australian conditions. 



