Dre ifax Delbruck.
California In&i&&e of Teotmology,
Pasadeua, Cal.

broh 28, 1938.

Dear Dr. DelbruckP

  I: wish f could attend the seU.nar you and Dr. PauUng are plan-
ning to run, although I fear my physical background would mt be &
quate,

  Lbatier serpfarate cover I am sending copier of the re@nte whleh
we still have, including the precipitin theory. I should be g&d to
have you return this the when you have finished ft.  I am ulwl mad-
bng the derfmtion of the three-staga 8@atio%l, although it does not
have to be used ia ptactice.

  I SUQI very glad that you are both interested in rerologluel,upm&
is&ity ami its lascmaas imd hope you will emerge with 4!#cmlew mmu
satisiaetory thaa our aaksshm.
ocfty a plausible one,       I thiuk your theory of Pu8dfou v8.b
          and mm a&x&, dtifusion com&mts will be JR&-

liahedway shortQby Kabstand Peasrsen iaWoience*, rothat youaa~i
be able to use them. I do not know, though, how you r5l.l. be able to
potash between the plliBsarlv union of mlfAv&twt amtLg8n 4 mlti-
rebut autfbody and the cwbaequsatuWms whichbuildupthe &%rge sg-
gregates which ult%s&ely separate.  f .bnagi.ne the veloaity mm% r;teb-`
crease grertly a8 th8 eqggregatt9 inCrsas%B in 8iS8, can YOU prorids se
a cxmstantly dininiahing oollfsion rate? Also, ti the ptw~plti.m mm==
tim between pneumococcus polysaccharides and potent anti&era vL8ibXe
reactfoa tak8s place &so?& instantly except at hi@ dilutirzrts and in
the cold, so that there ti no obvioue dhifereme between the &ge horse
and emU.rabbit antibody mlecules.  It ia e&a knorn that the tSl0city
of precipit&fon ti greatly influenced by the m, 8%~ that all of them
effects must be taken into account in B co~4plet8ly #satisfactory theory,

I&eaMr6d*                            raa actually
    Eagle has &so publiShed t5ome data uhich could be sxplalned
on almost my theory ~J.Irmsunul.bO,l8,393)~

  Our theoriee hirve been~attacked by EaUieZ and BoyU
37,663383), a@@BZWttzg PB a r8S-~t Of ZL C~l8t% ~i&UI&F8h#nfSi~ i&o
the range cwered by our antiMy ~ZCBQB equation, and by Booker mw3
Boyd [J,Ylmaunlf37,33,337 ), Ppstly becmae they fotil;etd to note t&t


the conditions of the experiment criticized eliminated the aibernaLiv8 they
zmggeat, and partly on the baais of their own experiments, the tecbn%qw mu3
subject matter of which are, I believe, open to some objection.

  Wishing you all success, and looking forrrerrd eagef&y to the result of
your deliberations,

Sincerely,