58 REPORT OF DEPARTMENT OF BACTERIOLOGY OF THE 
factorily and simultaneously. Accordingly we have been compelled 
to use a number of media. 
Our quantitative determinations were largely made upon whey- 
litmus gelatin. More colonies developed from cheese samples on ~ 
this medium than on the standard lactose gelatin. By its use most 
of the acid-forming bacteria can be distinguished from those that do 
not have this power. We did not observe that the litmus in this 
medium had any influence on the size, shape or structure of the 
colonies. In some cases it was observed that the color of some of 
the chromogenic bacteria tended to be obscured by the color of the 
litmus. A sugar-free medium was employed when searching for 
the liquefiers and non-acid-formers since many of these are sensitive 
to the acid which is developed from sugar in the medium by the 
lactic germs. Most yeasts thrive on cane sugar and tolerate an 
acid reaction so strong as to inhibit bacteria. From some of the 
cheeses we inoculated a series of plates of cane sugar media and 
added from 1 to 6 drops of a 25 per ct. tartaric acid solution to 
each plate at the time it was poured. For the sake of brevity and 
exactness the composition of these various media is summarized 
as follows: 
MeprAa UsEep IN INVESTIGATION. 









sare: Composition of the media. Reaction, 
number. 
Hagrame eet extractwGhiei1oS)) aes, cvs sbcakeee leMe emer. Per cent. 
5 pelle “AN ag Oa eet eee Oba an eee ae ln ee pny Giggs Bea = He ete 1.5 normal 
2.00 10 4 Pentone CWitte's) si aeaiens.cty eo ee ee oe acid to 
100 a CrelAatiny;, Kc kteaks Cot Le ne CARED eee ree attr phenolphthalein. 
1000 cc Waters distilled.) &.p.seaeeems -oo Sek eee eee ne ie 
Drerams beck extracha LAebie Samm rot sre ic ere eee ere 
2 INFACT See ee xis oor Bo ots bac Rea eee om eee Neutral to 
2.02 10 $ ReptonesG Wit teis) tae et ite ener Re eee phenolphthalein. 
100 cS Gelatin tas a2 eA soma a lise ee ote Ae rete cee 
1000 cc Weatern(distilled i. An Sie ents eee ete ee ee 
peeranis Deehextract ite DLeUS) ae meye ciel ere ae eee 
10 re Péentone (Witte Slee ope oe on ce eee ee ee 1.5 normal 
280 - OFA EN eh t eed ary ain Abt eC eS mas A cyt acid to 
PASO DE 1000 cc Water (distilled). cee ee phenolphthalein. 
LOo0 W bey oes Sad fae seh eee 
1COseranms Witmiusicwbessa ieee | fltrat 1.5 normal acid to 
500 cc Water (distilled)... /<2.5. 4 Shere ee phenolphthalein. 
grams Beef hase (Liebiots) eo. aioe eee 
S AC) codons ee va aencmoek « ovane e e 
10 rs Pedtone *(Witte's) mel. ace 6 ee eee ee Reaction 
2.31 120 © \Gélatini. ic5 cere eat, «2 ee eee not 
ne AY) s Canetsugar st it wees ct he eee adjusted. 
1000 cc Water (distilled). mas, ue tanl- « anche ener 
5 grams (Beef extractutlAecbigys) sce. «nc. eee eee 
5 = NaCl os) su ie eek a ee 1.5 normal 
3.00 10 “3 Peptone*(Wiitte's)-\. 0.0 6060 ce eee acid to 
1 + Agats J. re bora ene B.S te oe phenolphthalein. 
1000 cc Water - (distilled) 362 siee.. casein: cee eee 

a 
