April 6, 1893] 



NATURE 



545 



will be indicated by a deflection of the galvanometer needle and 

 a distortion of the lines of flow, usually designated by "nega- 

 tive rotation." In the case of a paramagnetic body the 

 rotation will be positive. 



Several correspondents have written to us with regard to 

 Mr. Hilderic Friend's letter on " Luminous Earthworms " 

 (Nature, March i6, p. 463). Several of them record obser- 

 vations which seem to them to confirm his statements. Mr. 

 R. I. Pocock, of the British Museum (Natural History), points 

 out, however, that the property of phosphorescence exists in a 

 highly-developed state in certain terricolous, nocturnal animals, 

 which, although both luminous and vermiform, are certainly 

 neither glowworms, nor yet earthworms. "The power of 

 producing adhesive phosphorescent matter from pores opening 

 upon the ventral surface of the body has," says Mr. Pocock, 

 "been recorded from different quarters of the globe, in the 

 case of several genera of centipedes of the family Geo- 

 philida ; and since no special affinity is traceable between all 

 the forms that are known to be sometimes luminous, it is 

 highly probable that the presence of appropriate glands for the 

 secretion of the matter in question is, or has been in the past, 

 characteristic of the whole group. About a dozen species of 

 Geophilida occur in the south of England, All may be 

 described as worm-like, and some of them are known to be 

 phosphorescent. Curiously enough, the specimens that have 

 been not uncommonly brought to the Natural History Museum 

 as phosphorescent phenomena are referable to a species, 

 Linotcinia crassipes, which is the most earthworm-like of all, so 

 far, at least, as colour is concerned. An example of this 

 species was, I venture to suggest, the 'luminous earthworm' 

 with the story of which Mr. Friend opens his account of the 

 subject. This centipede is about one or two inches in length ; 

 and, although it is impossible quite to acquiesce in the state- 

 ment that it is ' worm-like in all respects,' nevertheless I think 

 it more than probable that a lady, finding one in the dusk of 

 evening, when it could be but dimly seen, would summarily 

 describe her idea of its appearance by some such expression as 

 that used." 



Mr. J. E. Harting, writing in the April number of the Z^^^>§w/, 

 says that during a recent visit to Greece he lost no opportunity 

 of interrogating the natives as to the birds and beasts to be met 

 with, and was everywhere struck with the ignorance displayed 

 on this subject, and the general indifference which prevailed 

 respecting it. It was not until he reached the great plain of 

 Larissa, where a plague of field voles has been for some time 

 manifest, that he encountered those who could impart some 

 information on at least one small indigenous mammal, namely, 

 that which was causing'such mischief and pecuniary loss to the 

 resident land-owners. That it was a vole {Arvicola) of some 

 sort was certain ; but as to the precise species some difference of 

 opinion had been expressed. Mr. Harting gives much very 

 interesting information as to the animal's habits. 



A paper on the foundations of the two river piers of the 

 Tower Bridge, by Mr. G. E. W. Cruttwell, was read at the 

 last meeting of the Institution of Civil Engineers before Easter. 

 It was stated that the materials in the two piers, from 

 foundation line up to a level of four feet above Trinity high- 

 water (a height of 60 feet), consisted of 25,220 cubic yards of 

 cement concrete, 22,400 cubic yards of brick-work in cement, 

 and 3340 cubic yards of Cornish granite ; making a total of 

 50,960 cubic yards. 



The Agricultural Research Association for the north-eastern 

 counties of Scotland has issued its report for 1892. A general 

 outline of some of the past year's results is presented, and this 

 NO. 1223. VOL. 47] 



is followed by a record of observations, by Mr. Thomas 

 Jamieson, relating especially to grass and clover roots. 



Messrs. E. and F. N. Spon have issued a convenient 

 little volume of waistcoat-pocket size, containing electrical tables 

 and memoranda, by Prof. Silvanus P. Thompson and Eustace 

 Thomas. The type is small but clear, and there are some 

 illustrations. 



Messrs. Crosby Lockwood and Son will publish in a few 

 days a new work by Mr. J. D. Kendall, of Whitehaven, on 

 " Thejron Ores of Great Britain and Ireland," giving an account 

 of our present knowledge of the origin and occurrence of such 

 ores, and the means of reaching and working them. Some of 

 the more important iron ores of Spain are also noticed in the 

 volume. 



Dr. E. Symes Thompson will deliver lectures on the nose 

 and mouth at Gresham College on April 11, 12, 13, and 14, at 

 six o'clock. 



Until comparatively recently bacteriologists have regarded 

 the macroscopic appearances to which organisms give rise 

 when grown on potatoes as affording valuable assistance in dis- 

 tinguishing between otherwise verysimilar microbes. One notable 

 instance of this is the alleged different behaviour of the typhoid 

 bacillus and the closely allied B. coli communis when inoculated 

 respectively on to potatoes. But more recent research has 

 shown that as a diagnostic agent the potato is extremely untrust- 

 worthy, and this has moreover been conclusively demonstrated in 

 the case of just these two organisms. Further evidence on this 

 subject has lately been brought forward by Krannhals, " Zur 

 Kenntniss des Wachsthums der Komma bacillen auf Kartoffeln " 

 {Centralblatt fiir Bakteriologie, vol. xiii. p. 33), and the results 

 he has obtained in the case of the cholera organism are very 

 instructive. When cholera declared itself at Riga last August, 

 Krannhals, as Prosector and Bacteriologist at the city infirmary, 

 was deputed to demonstrate officially to the city medical authori- 

 ties that it really was cholera which had broken out. The 

 culture tests employed exhibited all the typical appearances 

 associated with the cholera organism with the exception of its 

 development on potatoes, upon which it obstinately refused to 

 grow. Suspecting that this might be due to the acidity of the 

 potatoes, slices were prepared and artificially rendered alkaline. 

 On these the bacillusgrew abundantly and moreover at from i6°- 1 9" 

 C, whereas it has hitherto been stated to be capable of only 

 developing on this medium at from 30°-40° C. On the acid 

 slices the same negative 'results were obtained as in all the 

 previous experiments. In consequence of this discovery Krannhals 

 conducted a large number of investigations on the behaviour of the 

 cholera bacillus on acid and alkaline slices of potatoes respec- 

 tively, and whereas he never failed to obtain vigorous growths 

 on the latter even at the low temperature, he was only in very, 

 few instances (4 out of 136 experiments) able to induce its 

 development on non-alkalised slices. But on testing those acid 

 slices on which growths had appeared, it was found that ihey 

 exhibited a distinct alkaline reaction. This alkalinity, moreover, 

 had nothing to do with the growth of the bacillus, for sterile 

 slices prepared in the same manner were tested both immediately 

 on preparation and after they had been preserved some days, 

 and the same astonishing result was obtained, i.e. that the 

 slices of potato originally acid had during keeping become 

 alkaline. Krannhals is led to suggest that in reality the cholera 

 organism is incapable of growing on acid potatoes and that in 

 those cases where it is stated to have developed on such, the 

 medium unknown to the investigator must have, as in his experi- 

 ments, changed from acid to alkaline. It is important that in 

 future, therefore, the reaction of the potato should be noted both 

 at the time of inoculation and later, when describing the growth 

 of organisms on this medium. 



