Iatcrta l%te

by F.H.C.Cxick

Studies on the  DhmIml proDerti.es of the cyto~%aam of
cells in tissue culture

.

  The general metlmd was BescribeR \in the report for the year
anding 94th %qdxmber *t948.     Rhce then the w&k has f+ollowed
two main li.rles.
1.  Experiments at room temperatures.   The loware temgerature
raducea the pertuxbatipns psaduoad by the living cell,
2.  Experiments on two non-biological materials having &II
elastic9ty of' the mme or&s cd magnitude as that of the
cytoplasm.  The materials were a dilute gel of' a cjlay, bentonfta,
and an elasth i%mp solution.

   A large number of oinematograph.films ham besa taken and
analysetd to obtain -the necessary curves of angular deflection
against time.  'P'he previous conclusimm about the elastk asd
,p2.astic nature of the cytoplasm have hem conflsrated and extended,
It has also b&en established Mat thg cytoplasm is thixotropic:
that is, that its *structure~~ oan be teroporarily destroyed by
mec;lanfcal agitation,   aqd IAat it is not "bigh3y ela8tkP
i.e. if a paxtfcle is dcsflectad rapidly t~raugh a large angle
it never feturns Gomgletely mbn tile couple is r0inove .  This is

in contrast to the betiavim of' the elastic soap, but in line
wtrith t%it 9i a vary feeble -gel 0-f bentmVe.

A paper is bsinp written* incorporating all these results
toget:ler witrJz the gefleral theoreti.cal treatment required. It
is at present in rough draft,

.


   As forshadomd bn WJ origtnal agplicatton, themfare,
T sh.~~.~lf!'lSke t.3 take up X-ray Crystallograghy, and to baccme
attaohsd to the 2l.R.C. grcnug at the Cavendstsh uaAer  Dr. .Parute;.
He ham au,ggested that 1 should tat&Is mmmtfn, a polypeptfde


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