was u s ed unh eated and al so h ea t ed for various periods of time. Cal c ium alginat e di s solved well in a solution containing unh eated sodium h e:xa metapho sphate solution and al m o st a s well in solutions containing
sodium h exametapho sphate solutions s t eam ed for 5 min and 1 5 min , resp ec tively. Solubil ities wer e unsa ti sfac tory in solutions contain
ing sodium h exam etaphosphat e s t eamed for
30
min and 60 min, respectively .Whil e th e resul t s wer e no t always consi stent , i t i s obvious that too much heat c oul d upset th e u s efulness of sodium h e:xame tapho sp}'l.ate solution wh en u sed for dis solving cal cium al ginat e in th e presenc e of Ringer ' s so lu tion . Auto claved sodium ho:xam etapho sphate solution was unsatisfac tory . Ten per c ent sodium h exametaphospha te solut ion s t eam ed for
i
h was sati sfac tory , and up to0 . 1 2
g of cal c ium alginat e coul d be sati sfac tori ly disso lved in a m ix ture o f1
ml o f1 0%
sodium he:xa metapho sphate solut ion thus treated and 9 ml oft
- s tr ength Ringer ' ssolut.:on .
Cons equently the s tandard prac tice was to pr epar e batch es of tub es of
10%
sodium hexam etc-.ph ospha t e soluti on , s t eam fori
h , and keep until r equired for ana ly s e s . This h eat tr ea tm ent i s more than adequat e to ' kill ' all l ac t ic s trep tococcal phage races which have been t e sted by o ther work er s.Serial decimal dilutions in
i
- s trength Ringer ' s solution wer e prepared from the solu ti ons containing dissolved c al cium al gina te.Quarter- s trength Ringer ' s solution was replaced
b,r
pep tone-sal tSurviva1 in Und i s sol ved Cal c i um and in Solution of Ca.lcitun
41
When c alc ium alginate wool i s u s ed for coll ec ting phage i t is som etimes n ec es sary to keep the alginate wool pad s for a ti me befor e estimating th eir phage c ontent. Experim ents wer e th er efor e carried out to investigate the effec ts of various keeping condi t ions on phage survival . A summary of resul ts i s shown ir1 Tabl es XIV and x:J'.
In th e ini tial exp er im en ts pads containing phage w er e prepared
by drawing ai r from a phage-laden atmo sph ere
(
aerosol)
through several calcium alginate wool pads h el d in a gl ass tube. In l a t er work the experimental pads were prepared by add ing smal l , measured amount s o f a d ilut ed wh ey suspension of phage to algi na te pad s . After pr eparation , phage was estimated in r epr esentative pad s , and th e r emainder were kep t under different c ondi ti ons and th en examined. In thi s way it c oul d be seen wh e th er the phage c ount rema ined cons tant or no t .Tabl e XIV deal s with pads impregna ted with phage from aero so l s .
I n Exp t 1 , phage-laden ai� was drawn through two 7-pad tubes. Analyse::t were mad e on al t ernat e pads , and the remaining pads were l oft overnigh t in th e r efri gerator , and were th en analysed.
(
T'n ere shoul d b� a r egular fall-off in amount of phage from fir st to last pads( 1 -7 ) .
f.eep ing in the refrigerator seem ed , if anything , to increase th e count. This method o f holding al t erna t e pads seemed unsati sfac tory , and was di scarded.
In Expts 2 and 3, th e pads , after aero sol treatmen t , were divided into approximately .equal par t s � One-hal f o f each wa s analysed o n the day of tr eatmen t . In Exp t 2 , corresponding halves were k ept overnigh t in th e r e fri gerator
(
dry)
. In Expt3 ,
al t erna t e pads wer e kep t in p ep tone- sal t solution at 4° C , and a t 22° C , overnigh t . Keeping by bo th methods s eem ed sati sfac tory.In Expt 4 , pads w ere divided after aerosol trea tmen t . One l o t was analy s ed the same day and the o ther l o t was kep t in pep to ne- sal t
solution overnigh t . Th er e were discrepanc ies wh ich may have b een due to uneven di s tri bution of phage on the pads.
In Expt
5,
after aerosol treatment of two tubes of7
pads each ,th e pads were divi ded. Hal f th e pads from both tub es wer e analysed immedia t ely , and the r emainder were kep t in bo ttl es wi th l id s on a t