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NATURE 



[April 4, 19 18 



Stream " current plays an important part in these 

 movements, he is led to the conclusion that food is 

 the influence immediately at work, these fish preying 

 largely on eel larvae or " leptocephalids," which, dur- 

 ing the summer months, are making their shoreward 

 migration from the Atlantic. "There would seem," 

 he remarks, "to be a close and even precise corre- 

 spondence between this periodic annual migration of 

 the Leptocephali and the appearance of the sun-fish 

 in our home waters." 



Mr. E. E. Green, in the Entomologist's Monthly 

 Magazine for March, makes a plea in favour of the 

 introduction into Great Britain of two species of exotic 

 butterflies. Mischief enough already has been wrought 

 in many parts of the world by experiments of this 

 kind, and it is devoutly to be hoped that further ven- 

 tures in this direction will not be made without the 

 fullest consideration of the possible consequences. 



The structure and relationships of Bathynella, the 

 European "well-shrimp," are discussed by Dr. W. T. 

 Caiman in a recent paper in the Quarterly Journal of 

 Microscopical Science (vol. Ixii., part 4, 1917). From 

 the study of a few fresh specimens from Switzerland 

 Dr. Caiman definitely confirms his long-held opinion 

 that this tiny, blind crustacean is a degenerate mem- 

 ber of the Syncarida, where it finds its place together 

 with Anaspides and the remarkable allied genera that 

 inhabit certain Tasmanian and Australian lakes, and 

 Palaeocaris and other fossils preserved in rocks of the 

 Palaeozoic era. 



The advance of our knowledge about the part played 

 by blood-sucking insects in the spread of disease is of 

 such importance and so continuous that the paper by 

 M. E. MacGregor {Bull. Entom. Res., vol. viii., 

 part 2, 1917), giving a summary of the recorded " In- 

 sect Vectors of Disease," will be of value for reference 

 by students. Ticks and other Acarina are appropriately 

 included in the tables, as well as true insects. Mr. 

 MacGregor warns the reader that his lists " can in no 

 way claim to be complete," but the omission of the 

 sheep-flies {Lucilia sericata, etc.) from "the chief in- 

 sects and Acarina that are directly the cause of disease 

 in man and his domestic animals " is somewhat sur- 

 prising. 



In a recently issued pamphlet, " Zur Auffassung der 

 Verwandtschafts-Verhaltnisse der Tiere, I," Prof. 

 J. E. V. Boas, of Copenhagen, speculates on the rela- 

 tions of the Echinoderms. He suggests that they were 

 derived, through the Crinoids, from a sessile polyp, and 

 he adduces in support of his view many interesting 

 resemblances of structure. Sedgwick showed how all 

 animals with a body-cavity distinct from the gut might 

 have originated from the Coelentera, and the article 

 " Echinoderma " in the "Encyclopaedia Britannica" 

 (1902, 191 1) applies this in more detail to the Echino- 

 derms. But the direct and easy transition imagined by 

 Prof. Boas fails to explain the peculiar torsion of 

 Echinoderm structure, or the traces of bilaterality the 

 existence of which he is bold enough to deny. Had he 

 remedied his admitted want of knowledge of some 

 English writings on this subject he might have dealt 

 with these difficulties more convincingly. Prof Boas 

 then proceeds to construct an ancestral worm (an " Ur- 

 Chaetopod," to be precise), from which he would derive 

 the Nemertines and flat-worms, the Enteropneusta, the 

 Chaetognatha, and the Brachiopoda ; and he connects 

 this ancestor with the Echinoderms by way of the 

 Holothurian Synapta. He brings out, it is true, a 

 number of interesting analogies, but most zoologists 

 would ascribe these to similarity in the mode of life. 

 A brief final chapter deals with the germinal layers 

 and the development of the coelom. The author insists 



NO. 2527, VOL. lOl] 



throughout that his hypotheses are possibilities rather 

 than proved theories. If they present difficulties even 

 as possibilities, we may none the less be grateful to 

 Prof. Boas for presenting ancient problems in a new 

 light and in a manner that is both interesting and easy 

 to follow. 



In the February issue of the Scientific Monthly, 

 published in New York, two interesting articles on 

 meteorology in connection with the war appear. Prof. 

 R. DeC. Ward writes about "Weather Controls over 

 the Fighting in the Italiaa War Zone," and gives de- 

 tails about the rain- and snow-fall and the temperature 

 during the past three years. The fighting has been 

 chiefly in mountainous regions, and the passes have 

 often been blocked by heavy snow. Prof. Alexander 

 McAdie deals with " Meteorology and the National 

 Welfare." A considerable part of his article is con- 

 cerned with the prevailing winds, such as the trades 

 and monsoons, and Prof. McAdie points out how the 

 character of a season in the United States depends on 

 the direction of the prevailing wind in that particular 

 season. He shows how aviation will depend upon a 

 knowledge of theje winds, and expresses the hope that 

 much information about the currents and temperature 

 of the upper air useful for meteorology will be obtained 

 by aviators after the war. In the same number of 

 the magazine there is also an article on " Snow and its 

 Value to the Farmer" iby Dr. Andrew H. Palmer, 

 which is interesiting and contains many good reproduc- 

 tions of photographs. 



Some experiments carried out at the Cancer Re- 

 search Department of the Middlesex Hospital are 

 described by Mr. J. C. Mottram and Dr. S. Russ in a 

 paper in the Proceedings of the Royal Society of Medi- 

 cine, vol. X. The paper gives a detailed record of ex- 

 perimental observations of a case of carcinoma imder 

 radium treatment. An ionisation method was em- 

 ployed to determine the intensity of the radiation 

 emitted by the several applicators used, and, in addi- 

 tion, measurements of the absorption of the /3 and y 

 radiations by the skin and subcutaneous tissues were 

 made. This was done in order to be able to compare 

 the effect produced upon the skin when it is irradiated 

 in such a manner that equal amounts of /3 and y rays 

 are absorbed by it. Details of the observations on the 

 skin and subcutaneous nodules subjected to screened 

 and unscreened /? and y radiations are given. As a 

 result of the tests it is established that, first, if the 

 skin is irradiated in such a manner that the neigh- 

 bouring portions absorb equal amounts of ^- and 7-ray 

 energy, similar reactions are produced, but they are, 

 in general, more pronounced in the case of the 7 rays. 

 Secondly, if the skin Is exposed to a large amount of 

 jS or Y radiation for a short time the reaction is more 

 pronounced than if the same dose Is given using a 

 smaller amount of radium for a correspondingly pro- 

 longed period. The effect on the malignant sub- 

 cutaneous nodules was not, however, appreciably 

 different In the two cases. 



The British Journal of Photography has reprinted 

 In its issues for March i, 8, and 15 a paper on "Axial 

 Aberration of Lenses," by Messrs. Tillyer and Shultz, 

 of the Bureau of Standards at Washington, which has 

 appeared lu the Journal of the bureau. After a clear 

 account of the way in which zonal aberration and the 

 sine condition affect the image, the authors describe a 

 modification of the Hartmann method which they have 

 introduced for the determination of the axial aberra- 

 tion of lenses and Instruments. In the case of a lens 

 monochromatic light of wave-length 4250, 4750, 5500, 

 or 6500 Angstrom units Is allowed to fall on a metal 

 screen seven metres away, perforated with holes a 

 millimetre in diameter and three millimetres apart. 



