April 14, 1910J 



NATURE 



ib9 



formalin fluid results in the destruction of the colour. I 

 am inclined to think that this destruction does not depend 

 upon the solution, but is due to the action of light. I 

 noticed the same thing in my experiments ; but, in addition, 

 I was enabled to observe — because I kept my rats in fiat 

 vessels standing on a blackened bench — that it was only 

 the upper surfaces exposed to rather bright sunshine that 

 thus faded. The under surfaces remained as brilliant a 

 yellow as before. To confirm this conclusion I placed all 

 my rats, still immersed in the solution, in a dark cup- 

 board, and the partially faded colour somewhat returned, 

 but not, I think, quite to the same intensity as originally. 

 So long as 1 kept them in the dark the colour was re- 

 tained. Whether this would be so indefinitely I should not 

 like to say ; but certainly it lasts for several months. 



The yellow tinge assumed by some albino rats is, I 

 think, not a phenomenon of light action, as Miss Durham, 

 quoted by Miss Sollas, seems to imply, so much as one 

 due to age. It is possibly a manifestation of diminished 

 metabolism and lessened oxidation. Of the several 

 hundred albino rats which I have bred, I do not remember 

 any within their first year showing this yellow tinge, while 

 it has been a frequent observation that old rats (after 

 about the first year), though they were kept in semi-dark- 

 ness, manifested a very obvious yellow colour. I do not 

 wish to commit myself to this as a positive statement, for 

 I made no scientific records of the matter. I am speaking 

 from general impression alone ; but it is certain there is 

 a marked contrast between the pure white hairs of young 

 rats, about six to eight weeks, and those of some twelve- 

 month or older rats, all living under the same conditions as 

 regards light. 



With regard to Miss Sollas 's experiments with the skins 

 of guinea-pigs and with that of a single mouse, there are 

 several considerations of interest that suggest themselves. 

 Miss Sollas found, as I did, that albino mice give a 

 negative result with formalin ; but I subsequently found 

 (Proc. Physiological Soc, October 23, 1909) that if pie- 

 bald mice are treated with 5 per cent, nitric acid in 75 per 

 cent, spirit and are placed in the dark, in about live days 

 most of the white areas of the pelage turn to a beautiful 

 rose-pink colour. The same is true of albino mice. These 

 experiments were performed in the summer ; but during 

 one cold week last winter I repeated the experiment on 

 a single black piebald mouse, and the colour-reaction 

 failed to appear. Upon placing the vessel containing the 

 solution and mouse in an incubator at 102° F., the rose- 

 pink colour appeared. The dependence of this colour- 

 reaction upon temperature is confirmatory evidence that 

 the phenomenon is one of ferment action. 



It would be interesting to see if guinea-pig skins, which 

 fail to respond to the formalin reagent, would do so with 

 the nitric acid. Geo. P. MuDGE. 



Biological Department, London Hospital Medical 

 College, E. 



The Electrification of Insalating Materials. 



Some time ago, while endeavouring to get a trustworthy 

 method of producing static charges in a humid atmosphere, 

 I had occasion to experiment with celluloid. Rolled 

 celluloid sheet with the surface burnished was found very 

 suitable. If a "tassel" be made of this material by 

 cutting up a small piece of thin sheet into narrow strips, 

 then by simply placing the " tassel "on a table and 

 stroking with the fingers, strong electrification is produced. 

 On raising the " tassel " the strips diverge, and remain 

 divergent in a most striking manner. 



A further curious effect was observed, that if two 

 narrow strips of celluloid were rapidly pulled between the 

 fingers they were both electrified, one of the surfaces in 

 contact being positive, the other negative. At first no 

 consistent results were obtained that might lead to an 

 explanation of the phenomenon ; some found the top strip 

 always positive, some the bottom strip when the pieces 

 were held horizontally. Later, however, Mr. M. McCallum 

 Fairgrieve, of Edinburgh Academy, noticed that the order 

 of electrification depended on whether the strips were bent 

 upwards or downwards when pulled in a horizontal direc- 

 tion through the fingers. This seems to be the true 



NO. 2III, VOL. 83] 



explanation. Of the surfaces in contact, one is in com- 

 pression, the other in tension ; with celluloid the com- 

 pressed surface is always negatively, the stretched surface 

 positively, electrified. The effect is very apparent if the 

 two strips are pulled slowly between the first finger and 

 the thumb, and the strip in contact with the thumb will 

 be -I- or — according as it is concave or convex to the 

 thumb. 



Of other substances investigated, paper, vulcanite, and 

 shellac have the same property, and mica to a lesser 

 degree. 



I propose to investigate the phenomenon further, par- 

 ticularly with relation to electrification by compression 

 and cleavage. In the meantime, L have made a small 

 electrical machine in which three endless bands of celluloid 

 run over pulleys. Suitable collectors are provided, and 

 considerable + and — charges may be obtained. The 

 charges are no doubt produced by the combined pressure 

 and bending, as already explained. 



Walter Jamieson. 



Provanside Higher Grade School, Glasgow. 



Effect of Varying Temperatures upon the Colour and 

 Growth of Fur. 



The following may be of interest to readers of Nature. 

 Some time ago an ordinary all-black cat was accidentally 

 shut up in a refrigerating chamber on one of the' Orient 

 Line mail steamers when the vessel was in Sydney 

 Harbour. The chamber was not opened until the ship^was 

 off Aden, which is about thirty-two days out. When- the 

 cat was brought out it was scarcely recognisable. . Its coat 

 had become long and thick, and the fur- on its back- was 

 nearly white. It had lost one ear through frost-bite. 



The change in the cat's environment from the intense 

 frost of a refrigerating chamber to the intense heat of the 

 Red Sea was accompanied by a rapid change in the cat's 

 appearance. The heavy white coat rapidly fell out, and 

 by the time the ship reached London the cat had practically 

 regained its normal appearance. 



I did not see the cat, but have inquired carefully into 

 the statements, and have had their truth vouched for by 

 one of the directors of the Orient Company. 



A. Campbell Geddes. 



Royal College of Surgeons in Ireland, Dublin, 

 April 6. 



April Meteor Showers. 



In the present year there is likely to be a greater 

 amount of meteoric activity about April 1S-19 than, "as 

 might be expected, a few da3's later. There will then be 

 an interval of quiescence until April 26. Between the 

 latter date and the end of the month several important 

 displays become due. The following are details of the 

 most interesting showers, as calculated by the writer, that 

 occur during the period April 12-30 : — 



Epoch April 19, i4h. 30m. (G.M.T.), shower of second 

 order of magnitude. Principal maximum April 18, 

 22h. i8m. ; secondary maxima on April 19 occur at 

 ih. 12m. and gh. 25m. 



Epoch April 27, 2ih. 50m., shower of twenty-third order 

 of magnitude. Principal maximum April 26, i6h. 26m. 

 On April 26 there are also secondary maxima at 5h. 20m. 

 and i8h. 55m., and another on April 27, 6h. 



Epoch April 28, iih. 15m., shower of fourteenth order 

 of magnitude. Principal maximum April 30, 4h. 25m. 

 There is a secondary maximum on April 28, i7h. 30m., 

 and two others on April 29, at i2h. and 2oh. 20m. 



Epoch April 29, i2h., shower of fourth order of magni- 

 tude ; the principal maximum becomes due about 

 April 28, i2h. 



While there are three meteor showers that fall between 

 April 26 and the end of the month, there is only one of 

 any importance during the period April 12-25. In some 

 respects this earlier isolated display is the more interest- 

 ing, however, owing to its being of greater intensity than 

 the others, and of a somewhat different character. 



Dublin. John R. Henry, 



