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NATURE 



[November 



17 



while his book will shock a few righteous who 

 need no repentance, and afford erotic stimulus to 

 a few abnormal people to whom even the lilies 

 of the field are "sugg-estive," it will, we think, 

 be welcomed by teachers, by parents, and by the 

 quite naturally curious adolescents who find in all 

 our highly evolved educational system nothing 

 corresponding with the ancient initiation into the 

 mysteries of sex, and very little corresponding with 

 the ancient disciplines correlated with these. 



Dr. Herbert's account of ovum-maturation is no 

 longer quite correct; his reference to Loeb's 

 method of artificial parthenogenesis is not up to 

 date; to call the female organism or sex-cell 

 anabolic and the male katabolic is a false sim- 

 plicity, for it is a question of ratio, as when 

 Riddle says of pigeons that the ova which show 

 a relatively greater storing capacity and relatively 

 lower intensity of metabolism develop into female 

 organisms. But these are minor points ; the bulk 

 of the book is thoroughly competent and sound, 

 and this has been wisely restrained. Its par- 

 ticular excellences are in calling a spade a spade, 

 in considering sex in mankind as the outcome of 

 a long evolution, and in insisting on treating 

 the problems not .merely physiologically, but also 

 as problems of psycho-biology. 



Insetti delle Case e dell' Uomo e Malattie che 



diffondono. By Prof. Antonio Berlese. Pp. 



xii + 293. (Milano: Ulrico Hoepli, 1917.) Price 



4.50 lire. 

 Prof. Berlese's interesting manual deals with 

 the insects and arachnids found in Europe attack- 

 ing man or damaging his food and belongings. 

 After considering those — lice, bugs, fleas, mos- 

 quitoes, Phlebotomus, Stomoxys, and ticks — which 

 suck the blood of man, he proceeds in the two 

 following chapters to give an account of house- 

 flies, blowflies, etc., and of such household pests 

 as cockroaches, psocids, Lepisma, moths, and 

 mites. Under most of the species there is a short 

 description of the adult and of the life-history and 

 habits, and suggestions for the application of 

 deterrents and destructive agents. In several 

 cases, e.g. the plague flea, the characters are too 

 briefly given to be of much service. 



The fullest accounts are those of mosquitoes and 

 house-flies. The author describes his successful 

 attacks on house-flies by means of a solution of 

 sodium arsenite (2 per cent.) and molasses (10 per 

 cent.) in water, and recommends, as the result of 

 his experience, that this solution should be sprayed, 

 every eight or ten days during the fly season, on 

 plants near houses and on manure-heaps, and that 

 bunches of straw or twigs should be dipped in the 

 solution and hung up outside houses near the doors 

 and windows. 



A short final chapter is devoted to spiders, scor- 

 pions, pseudoscorpions, and acarl, which attack 

 some of the pests before-mentioned. 



There are a hundred figures in the text. The 

 legend of Fig. 24 is misleading; the figure repre- 

 sents the head of a larval Simulium, not, as stated, 

 the head of a larval mosquito. 

 NO. 2505, VOL. 100] 



LETTERS TO THE EI>ITOR. 

 [The Editor does not hold himself responsible for 

 opinions expressed by his correspondents. Neither 

 can he undertake to return, or to correspond with 

 the writers of, rejected manuscripts intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



On an Appearance of Colour Spectra to the Aged. 



During the latter months of my eighty-ninth year 

 my attention became directed to a circular colour spec- 

 trum which appeared to surround any bright light 

 to which my eyes were directed. The condition was 

 new to me. I had never read of its occurrence, and 

 had never heard it complained of by a patient ; but on 

 making inquiry of two distinguished ophthalmologists 

 of large experience I found that they had 

 been consulted in similar cases, one of them 

 only by octogenarians, while both mentioned 

 examples in which the appearance had excited grave 

 apprehension and distress. But nothing, so far as I 

 can ascertain, has appeared in print upon the subject; 

 and I am inclined to attribute my own lack of experi- 

 ence with regard to it to the fact that I retired from 

 practice fifteen years ago, and that domestic lighting 

 by electricity, which supplies conditions very favourable 

 to the production of the appearance in question, has in 

 the meantime become increasingly prevalent. I will 

 endeavour to describe what I see. 



If I look steadily at an ordinary electric filament 

 light, about 10 ft. distant from my eyes, it appears to 

 be surrounded by a vivid colour circle about 2 ft. in 

 diameter, with the red band external, the blue internal, 

 the yellow intermediate. The band appears to be about 

 6 in. in width, so as to be quite clear of the light 

 itself, from which its inner margin appears to be about 

 6 in. distant. If I light a wax match and hold it in 

 my hand, the colour circle around the flame appears 

 to be about as large as a florin, while that around a 

 full moon is ver}' large and of very brilliant colours. 

 The appearance is most striking when the light is near 

 enough to be vivid, and yet distant enough to fall upon 

 the eye in a slightly divergent pencil, a result well 

 obtained by seeing in a mirror, at 10 ft. from my eyes, 

 the reflection of an electric lamp 10 ft. from the mirror. 

 This arrangement furnishes a circle about 3 ft. in 

 diameter, both larger and better coloured than if I look 

 directly at the lampf itself. 



I do not think that the optical condition of my own 

 eyes has ariy bearing upon the matter, as the presence 

 or absence of spectacles makes no appreciable differ- 

 ence of luminosity or of colour; but the facts are that 

 my right eye has a total H. of 2 D., with i D. more 

 in a nearly horizontal diameter, and my left a total 

 H. of 250 D., with 1-50 more in a similar diameter. 

 For the last forty years I have constantly worn fully 

 correcting spectacles, with an increase in the lower 

 halves of the lenses for presbyopia, as it gradually be- 

 came established, and my vision is, and always has 

 been, perfect. I watch with pleasure the evolutions 

 of distant and lofty aeroplanes, and I read "brilliant" 

 type with facility. 



If a strong light is brought sufiiciently near my eyes 

 to produce active contraction of the pupils the colour 

 circle does not appear, but it springs Into" existence as 

 the light is moved a few feet away and the pupils are 

 suffered to expand. In like manner, the colour circle 

 Is obliterated when I look at the moderately distant 

 light through a pinhole opening In a card or thin metal 

 disc. The facts appear to be that when the eye receives 

 onlv a small pencil of nearly parallel rays these are 

 sufficiently refracted In the ocular media to be united 

 In a focus upon the yellow spot. When It receives 

 a larger pencil, the outer portions of which will be 



