234

NATURE

February 9, 1952 voL. 16~

LElTiRS bT0 THE EDITORS

synthetic Polypqddos

8ppli68Wh66lth08Xi8l-~~-~
turMofthehelixi9P,thed-betweenthe
-sfome1yinsOntheh&Xi8p,8Wldfhe
sttu&weofornKdierepeefedWyinctaeriel
dietsme c. (For the l&em condition fo be pomible, P/p
must be expremible 80 the r8tio of whole numbem.)
rntbiBoam*thetr8n6fo~ieratri~fop~in
WipXl8l#lptWXJWhiChSre~CUl8?tOth~8Xi9
of~he~,cmdoccu8t~~~~~~~~,w~~ie
BP ilttqpr. Jn tNptallogr8phie nome4lelsture, thale
~tbbb~lineeCOrreepoIldingtO8UIIitdOf
length G. On the Zth rmh pkne the tr8Mbrm ham
the vshle:

fnrpolypepta,butfordloffhm,P,prrado
arot&mme,slthough~ia~erent. Thebadmof

slimittathe,vshteof~~~~thaparfofthe
tr8nufmmcxnwredbytheobmrveddS8otionpiofure
(z3<0~8kL-`forzoh'O). N0mtof8tonml?anm8k0
8n sppreokble oontributioll to the 8mplitude of 8
refledOn~msl8yerlineWithWhiob~y
high-order Beam1 fuxl&ioM 8re 8seooi8w beo8lme
2%ZZ~llOIO66WithillfheVerglOWperfOfth6J~
in the graph.

We should therefm prediot fbst layer linea to
whieh only hfgh-order B6mJeJl iblletioxl9 Qontriw
wouhibew6skorsbeemt,8ndth8tthoe9towhiCh
very low ordera eontribute would be &mm&

of the table. The G@&mnt Bawl funotiona invohd
iuthe~tweulty=eight~yeriiueutueebownin
themcondoohmm,end,8ewillbeee6n,onlyl8yer
linea8mwi8~with8f\llmtionoforder4orless


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