SCIENCE-GOSSIP. 



3^5 



I'Ar.n. Alwiit 0.48 mm. Vmf,, with three- i>e(»s on 

 ihc inner curve of ihc fourlh segment. 



Gkniiai. .\rka. — Conipiisetl nf four plates on the 

 extreme posterior margin (tig. 6). The two lower 

 plates contain three discs each, the two iip|K'r only 

 two each. 



Male. —Similar lo female, except in the genital 

 plates (fig. 7). litre again wc liiid two |)l;itis, willi 

 five discs on each plate. 



I.ocAi.i r IKS. — Kound free-swinnniiig in clear 

 water, at llighams I'ark in .Middlesex. Iiy Mr. 

 Taverner. Several were taken, and a few nymphs. 



3. Atu.\ fii^iiralis Koch. 



I'K.MAl.K.— Kody ahout I.25 mm. long. Tale 

 yellow in colour, with brown markings ; it has two 

 very small papillae on the posterior margin, hnl 

 nothing to be compared to the size of those on 'lie 

 two previous species. 



Lei;s. — l-'irst pair about 1.64 umi. Second pair 

 alx)Ht 2.58 mm., which, like Alax crassipis, are the 

 longest pair. The first pair arc not quite so thick 

 as the first pair of ./. crassipis, but they possess 

 similar long, strong spines. 



Ei'iMERA. — In four groups (similar to fig. i). 



I'.Ai.j'l. — Rather short, being about 0.40 mm. 



Geniiai. -Vkka. — Kour plates, very much like 

 A. Idventiii, having three discs in the lower plate 

 .-ind two in the upper one. They dilTcr in this respect 



iMi;. 



A, yig'iiraiis. (iyn 



from A. laveriieri, which has the three lower discs 

 nearly in a line, while in A. Jif;iii-alis they are so 

 placed as to form an angle. 



Male. — Very much the same as female, except in 

 genital area. Here we have two plates, with five 

 discs e.ich, but arranged quite diflerently from the 

 male of A. laverneri (fig. 8). 



LoiAl.lTiES. — I have found only three specimens, 

 two females and one male, in September, 1898, on 

 the Norfolk Kroads. 



( To be eoiitiniicd. ) 



New Catai.oc.I'ES. — Messrs. Xachet et Fils, ol 

 Paris, send us their catalogxie of Microscopes and 

 accessories. Messrs. Bausch & Lomb Optical Com- 

 pany, of Rochester, X.Y., send us catalogues of 

 Photographic Objectives, Shutters, iSic. ; also of 

 Chemical Apparatus and Reagents. The latter firm 

 have in the press new catalogues of Microscopes and 

 accessories, which we will deal with more fully when 

 they reach us. 



11 II". x.Mi UI-: OK i,ii-i<:. 



liv I-. .1. Ar.i.EN, .M..\., M.l). 



TT.WINCi for many years made a careful study 

 ■* ■*■ of the funilaniental chemistry of life, I hope 

 I may be alloweil to offer a few comments on 

 Mr. (ieoflVey Martin's paper, " Life under i;ther 

 Conditions," in your issues for March and April 

 (aiiti, pp. 291, 326). 



I have given a summary of my views on the 

 nature of life in the Proceedings of the Birmingham 

 Natural History and Philosophical .Society for 1899, 

 lo which I would refer .Mr. .Martin and others in- 

 ti'rested in the subject. Life is too complex to he 

 defined in a concise aphorism. .All definitions as 

 yet given have missed the mark ; and Mr. Martin's 

 definition of life as " organised motion " is not more 

 successful than the others. In order that it should 

 convey a definite meaning we must first understand 

 what organisation is. Does life depend on organ- 

 isation, or orgai\isation on life ? John Hunter taught 

 the latter, but perhaps the discussion is an empty 

 one, for lifi and o)-i;aiiisation are almost synonymous 

 terms. 



The most fundamental physical phenomeiKm of 

 life is the energy Iniffli, or the function of trading in 

 energy. The chief physical function of living sub- 

 stance is to gather up radiant energy {e,g. from the 

 sunshine), store it in the potential form, and after- 

 wards to disperse it in the active or kinetic form. 

 The complex chemistry of life diflers from other 

 kinds of complex chemistry, such as that of the 

 silicates, in that the former entails great changes of 

 energy, whereas the latter does not. 



In seeking an explanation of the chemistry of life, 

 investigators have confined their attention too ex- 

 clusively to the properties of carbon. If they had 

 given equal attention to nitrogen, they might have 

 realised long ago that the most characteristic phe- 

 nomena of life are due to this element. The intense 

 instability or "lability" of living substance is a 

 specialised form of the lability of nitrogen com- 

 pounds, as seen in gun-cotton, nitro-glycerine, ful- 

 minic acid, " lyddite," etc. These compounds are 

 formed of the same elements (nitrogen, oxygen, 

 carbon, hydrogen) that form the bulk of living sub- 

 stance. Nitrogen combines readily with many other 

 elements, but has no strong attractions and few 

 preferences, the result being that its compounds are 

 the most changeable on earth. They are also the 

 most various in their properties. Compare nitric 

 acid, ammonia, cyanogen, azo-iniide, etc. In short, 

 nitrogen may be calle<l the <ri/ital element of this 

 world, i.e. the element which under the given cir- 

 cumstances is alw.ays wavering as to its slali.' "f 

 combination. 



Carbon, on the contrary, has one overruling 

 attraction — namely, for oxygen. It would exist on 

 this earth in coinbination only with oxygen, as 

 carlion 'dioxide and carbonates, were it not for the 



