724 



NATURE 



[November 17, 1923 



I- scattercil radiation through the 



and throuKh tfif absorbrrs, 

 .ippjirentK <!: 



<)l)taJned i 

 now SUggrst 

 taking otner v 



use soft rruliai i 

 absorliii-. 1 . 



difficnli \ Ml 111 



■iirmuiifMlii iti 



I Miiijmni in.ii, 111 .Ki'iiuoii lo 

 MS precautions, he might also 



\-i\ thin rruliators, and vcrv tl;:-- 

 1(1 Milt Ihiiilv ill- will llicii iia\i- nil. 



ll.lll"" ' ■ it!.'.-! 1 wli i I .. .;i \ ,-I\- Ilk, 



the iiiini.tiA aiul \ 



j^n en li\ 111 , !i .1 I!!!. 



sIh ii ti'i \\ , 



Ith He (llllli lilt 



piiiflratiiig j)i' 



as usually cletectci 



t 'vswuM be 



.in^li ii iii.it n i iiations of 



I \\ ill iiiih ' il is much 



ii aiulluii^ lii<c (•<nialit\' of 

 Accii [)riiii.ir\- ami srattrrcd 

 luit an explanation ol this 

 can be given, — not the nltimate explanation, but 

 ."■Mil in terms of the J ti .in .ti urinations. 



I uiilu T, let us ixaiiiini- the theory of the recoiling 

 cltiiMins. Giving the Coiiipton fonnula tlie In-st 

 cliaiur of success, consider what would haj)pfii to 

 the I It I turns in liydrogen which require little energy 

 III! thru (xt I ait ion; These electrons scatter as 

 iiuK h as ,1 similar number in other substances (Barkla 

 and (row then. A simi)ic calculation shows that when 

 the K iiidiutiou ol tm is employed, the recoil electron 

 should produce an ionisation of the order of i/iooth 

 part of that produced in air by the same X-radiations 

 through the ordinary long-range electrons. Now 

 Shearer in this laboratory observed in hydrogen an 

 ionisation as low as o-ooi6 of the ionisation in air; 

 and remarked on the strong probability of this being 

 an over-estimate. This would be of the right order ot 

 magnitude for the effect of long-range electrons alone. 

 Where then is the effect of ionisation by Compton's 

 scattering electrons ? It apparently does not exist. 



The evidence Compton used and obtained from the 

 study of 7-rays is necessarily much less trustworthy ; 

 the experimenters have probably never — indeed cannot 

 have — realised the many possibilities of error. Any 

 transformation to a softer type — or at any rate 

 something equivalent to that — would entirelj'^ vitiate 

 the results obtained both in absorption and scattering 

 experiments. Without wishing to detract from the 

 merit of the work, one may justifiably point out the 

 difficulties of exact measurement in this region. One is 

 led to ask : Are experiments on the diminution of 

 scattering really trustworthy ? Accurate they cannot 

 be ; they may be entirely misleading. Thus in cases 

 we have investigated, Compton's formula holds neither 

 for the apparent change of wave-length, nor for the 

 energy of the recoil electrons. But we can quite easily 

 get many of the effects of the kind Compton considers. 



It is possible that the J transformation which we 

 have observed will be explained by a theory bearing 

 some resemblance to that of Conipton for so-called 

 scattering. This would be supported by the evidence 

 of C. T. R. Wilson's " fish-tracks." It seems un- 

 fortunate that Prof. Compton should have applied 

 the term scattering to a hypothetical process which 

 is so essentially different from the scattering of 

 X-rays as ordinarily known. The important con- 

 clusion is this — the results of experiments on scatter- 

 ing and the Thomson theory explaining these are 

 absolutely untouched. 



Many of the experiments upon which these con- 

 clusions have been based were obtained in collabora- 

 tion with Mr. Khastgir and Mr. Stevens, in addition 

 to those already mentioned. C. G. Barkla. 



University of Edinburgh. 

 November lo, 1923. 



•S< Names «! 



f AM gia-i mat Sit CUfior< 



>ber 20, p, 590, supports th 



for 

 ur,' 



i h 



OSaurui. t /iiiv a 



nt pronounce the 



one in liuxiera Laimi 



mi-fliphthong ei couldl 



' t(;r in our script,! 



\\c-\ for those wnol 



<"»reek orl 



icised inl 



; egret, M 



- attempt I 

 - for some centuries converte<l the Lai 

 and oe (for the Greek ni and oi] into t 

 <£ and ce in manuscrij 

 no classical authorit' 

 much ad van- 

 texts. TheGi 

 not well be 

 and this fact 

 join a and o 10 c m 

 Latin. Where the \s 

 form, as ccenosarc, or 

 not a generic or specify 



will remain compounder , i^ui »i: jna% , 1 uiiuk "luij 

 wisdom, write Coeloptychium and Taenia. Moeri-I 

 tlieriuiu is a case that needs attention. Thf- '''^■' 

 Museum, which has an honourable vested in 

 the mortal remains of this fascinating creatufL, ... 

 the o and the e separately. The Americans, and nov 

 the Japanese, adopt tlie comuounded form. 



Dr 1. ( I'ur cr ti onfide all my classicall 



trouble-, tell> me tiial ; : ;s fBook II., I48) givesl 



the lake in the I'ayuni as </ lojpcot, named! 



from a king who would appea un as Moeris. 



(". Stephaiins (" Dictionarium hiitoricum." a.d. 1633)! 

 ])rint^ ■ Mo ridisstagnum " ; but here again the separa- 

 tion of the and e would seem ad\ ' 

 that I always write Cainozoic in pre 

 zoic or Ca;nozoic, though the <5P conforms L>e-t witn uurJ 

 general usage. This term, however, never had a Latin| 

 form, and mav now be T-cuarded as an ICnylish word. 



As 1 remarked in my note in XAirKi. for July 

 (p. 10). it is now (littieult to be logical. The Ency-" 

 clopa-dia IJritanna a gives us an article on Deino-| 

 theriuni, but makes us look under di for deinc>saurs.< 

 Following Sir Clitford Allbutt, let us help pronounc 

 — and printer-s — where we can. 



Gkenvillk .\. J. Cole. 



Carrickmines, Co. Dublin, October 28. 



Is the Pentose of the Nucleotides formed under 

 the Action of Insulin ? 



In a letter to Nau kk for June 16. p. 810, 

 Winter and Smith directed attention to their obser\ a-j 

 tion that the blood and certain other tissues of the! 

 rabbit contain, after injection of insulin, a substance! 

 which reacts as a carbohydrate towards the a-naphthol 1 

 test, but has no reducing action on copper salts even! 

 after acid hydrolysis, (omnienting on this they say : 

 " It seems possible that the carbohydrate content of 3 

 the animal body may l^e not appreciably diminished 

 after large doses of insulin. The above facts would 

 suggest that the sugar storefl in the bo<ly as ghxogen 

 is converted into this peculiar form." 



If I understand the suggestion correctly, it is that 

 this unidentified carbohydrate substance is formed ; 

 from glucose under the influence of insulin. If thisj 

 is so, it should be present in normal blood and other] 

 tissues, but absent from tliose of diabetics. 



Jackson has recently shown (/. Biol. Chem., 1923, 

 Ivii. 121) that adenine nucleotide occurs in normal 

 human blood. I ha\ e myself recorded its occurrence, 

 together with other imcleotides, in the pancreas of 



NO. 2802, VOL. 112] 



