January 6, 1921] 



NATURE 



599 



Socit'ty and other loading learned sixieties in this 

 matter. The British Science Guild has kindly granted ■ 

 the committee permission to use its address. 



\Ve appeal for subscriptions, and ask that cheques 

 should be made out to the Treasurer, C. Hagberg 

 Wright, LL.D., and sent to the British Committee 

 for -Aiding Men of Letters and Science in Russia, 

 British .Science Guild Offices, 6 John Street, .\delphi, 

 London, \V.C.2. 



MoNT.XGL' OK Beaulieu, Bern.xkd Pares, 



Krnest Barker, .Arthlr SciifsTKR, 



K. P. Cathcart, C. S. Sherrington, 



.\. S. Kddington, a. E. Shipley, 



I. GOI-LANCZ, H. G. Weli-s, 



R. .\. Gregory, A. Smith Woodward, 



P. Chalmers .NIitcheli., C. Hagberg Wright. 



The Pea-Crab 



{I'innothercs pisum). 



There is an apparent discrepancy between Dr. J.H. 

 Orion's interesting description of the pea-crab in 

 Natire of December 23, p. 533, and that given by 

 Dr. W. T. Caiman, whom he quotes. Dr. Orton attri. 

 butes the impunity with which the male crab and the 

 male-like female sustain the nip of a bivalve to 

 their "extraordinarily strong carapace" (p. 534). 

 On the other hand. Dr. Caiman, discussing whether 

 the Pinnotherid crabs should be reckoned commensals 

 or parasites, observes that they " show one of the 

 characteristics of parasites in being to some extent 

 degenerate in their structure. The carapace and the 

 rest of the exo-skeleton, no longer needed for pro- 

 tection, have become soft and membranous " {" IJfe 

 of the Crustacea," p. 217). 



Docs not Dr. Caiman's suggestion tend to confound 

 racial degeneracy (such as environnrent has imposed 

 upon Crustacea and fishes inhabiting subterranean 

 waters, or such as has been induced by habit of life 

 on certain parasitic species of Hemiptcra) with modi- 

 fication of growth and adaptation of functional activity 

 in individuals approaching parturition? If the female 

 crab does not, after moulting within the bivalve, re- 

 new the hard carapace which protected her in obtain- 

 ing entrance, the diversion of nutriment to her swell- 

 ing spermothecae can scarcely Ik* accounted de- 

 generarv. Rather it suggests analogy to the extreme 

 rase of Termes hellirosus, the so-called white ant, 

 which is neither parasitic nor. presumably, racially 

 degenerate, but the qufen-mother of which is peren- 

 nially and unintermittentlv parturient, with the result 

 that, according to Smeatham, her alxlomen "grows to 

 such an enormous size that an old queen will have it 

 increased so as to be fifteen hundred or two thousand 

 tiines the bulk of the rest of her bodv." and twenty 

 or thirty times the bulk of one of her worker 

 offspring. 



Dr. Orton having carried research into the pen- 

 crab's life-historv a stage further than Dr. Caiman, it 

 is to bo hoped that he will soon be able to announce 

 a complete solution. IlKHnFRT \f\\«Fii. 



Monreitii. 



The Mechaniei of SoNdity. 



Iv connection with the rnrrespondence on this sub- 

 ject in Naturk, attention may h«- directed to the 

 attempt* made by C. Benedicks (Zfil. f. anmg. Chrm.. 

 vol. xlvii.. p. 4.^."!. t'toa; Ann. d. Phv^ik, vol. xlii.. 

 p. IS3. lo'."}) to relate the hardness (II) to the other 

 physical properties tif the suhsl.-inre. He suggested 

 that H is inversely proportional to the atomic volume 

 (V) nrki to the coefficient of rxpnnsion (a), and there- 

 fore WVa is constant for different elements. This 

 result includes the relation given by Mr. J. Innes 

 (Natirr. Novemlier iH). Benedicks also propoM-d a 



NO. 2671. vol.. 106] 



new formula for the characteristic frequency (v) of 

 an element of atomic weight .\ in the solid state. He 

 assumed that the frequency is proportional to 

 V(H/.\), and hence to ^(i/VoA). If the further 

 assumption be made that the frequency so determined 

 is identical with the frequency given by one or other 

 of the tormulce summarised by .\lr. V. T. Saunders 

 (Nature, December 23), other relations between the 

 physical constants may be obtained. For example, 

 according to the Sutherland-Lindemann formula v is 

 proportional to VIT./.WI), where T, is the melting 

 point on the .Vbsolute scale. Combining this with the 

 previous result, we find oVlT, = a constant, a relation 

 given by Pictet in 1879. 



I cannot altogether agree with Mr. Saunders 

 (Nature, December 23, p. 534) in his omission to 

 consider the hardness in relation to other physical 

 constants mentioned on the ground th;it it is a sur- 

 face effect and noi a bulk effect. .Mthough the condi- 

 tions at the surface differ from those in the interior 

 of the solid, those conditions are determined bv forces 

 of the .same general character in each case. In the 

 case of a liquid a large number of relations between 

 surface tension or intrinsic pressure and other physical 

 and chemical constants have been given, and Lapl.ice's 

 theory points the way towards the co-ordination of 

 these results. Reference may be rrjade to the book 

 by Willows and Hatschek on " Surface Tension ;md 

 Surface Energy " (Churchill), in which this matter is 

 discussed, and the conclusion that solids ought to 

 possess surface tension and intrinsic pressure is 

 emphasise<l. .Mr. Saunders, if he is to be consistent, 

 should omit reference to the melting point as well 

 as to the hardness value, since a pure crystalline 

 solid melts on the surface only, and the melting point 

 is the temperature at which the solid can exist in 

 equilibrium in contact with its own liquid under a 

 specified pressure. 



Mr. Saunders is no doubt correct in maintaining 

 that further attempts to relate mechanical and other 

 physical constants of solids must be based on modern 

 theories of the structure of the atom. 



H. S. AiiEN. 



The University, Edinburgh. 



The Meteorology of the Antarctic. 



In the preface to my book on Antarctic meteorology 

 I wrote. " I was recalled to my work in India when 

 the Terra Nova returned to the .\ntarctic in January. 

 U)i2," and the reviewer in Nature of December 23 

 (p. 528) has very naturally concluded that this me;mt 

 that I was recalled officially by the Government of 

 India. It is, therefore, only fair th;it I should state 

 the facts. I was granted thr<'e years' leave by the 

 Government of India, which would have been suffi- 

 cient if Capt. .Scott's original pl.in of staying only one 

 vear in the .Antarctic had been carried out. When, 

 however, it was clear that the expedition would 

 remain two years, I told Capt. .Scott that I would 

 stay the second year and write to Itnlia asking for my 

 leave to be prolonged. Wlieii the Terra Nova arrived 

 in January, iq\2, she brought me a li'tter from Mr. 

 Field telling me that Dr. Walker had gone to Eng- 

 land seriously ill. and that he himself was so unwell 

 that he did not see how he could carrv on. In these 

 circumstances I felt it was my duty to my colleagues 

 in India to return at once. 



I think most people will understand how in such 

 circumstances I came to write that I was " rernlled " 

 to Imlia, but it was an unfortunate expression, and 

 would not have been used if I had realised the infer- 

 ence which would be drawn from it. 



G. C. Simpson. 



Mrteorologicnl Office, Ix>ndon, December 17. 



