New York AGRICULTURAL EXPERIMENT STATION. oF 
amount added to a plate is figured on the basis of the total volume 
present at the end of the grinding process. The former method is 
the more convenient as the dilution factor can be figured in advance 
and the dilution is always expressed in round numbers. According 
to the second method the actual volume of the emulsion is de- 
termined and this value used in the computation. In our work we 
followed the latter method and as the average determined volume 
of the emulsion, when 30 cc. of water had been added, was 33 cc., 
our numerical results are 10 per ct. higher than they would have 
been if calculated on the other basis. 
Green cheese has a very large germ content, one of those studied 
showing 178 millions per gram. As the cheese ripens the germ 
content diminishes until in a ripe cheese only a few thousand per 
gram may be found. In order to get a good development of the 
colonies and thereby assist in the provisional separation into kinds 
of germs present there should be only a few hundred colonies on a 
plate. Accordingly, the amount of dilution is of considerable 1m- 
portance. It has been the practice in this work to make at least six 
dilutions ranging from 1I-—1000 to I—200000 and three sets of such 
dilutions, 18 plates, were made from each sample. 
While these high dilutions provide for the formation of char- 
acteristic colonies they have the disadvantage of cutting out those 
forms which are present in the cheese in comparatively small num- 
bers. The occasional representative of these scattering forms which 
appear upon the plates ‘can not be distinguished with certainty from 
the occasional isolated colony brought in accidentally from the air, 
and is accordingly rejected. There seems to be no satisfactory 
remedy for this difficulty since with less dilution these forms are 
either crowded out or are overlooked on account of the small size 
of the colonies on heavily seeded plates. A partial remedy is found 
for certain classes where special treatment reduces the competition ; 
as where the material is heated to kill all but the spores, sugar is 
omitted to discourage the acid formers or sufficient acid is added to 
inhibit all but the yeasts. 
; MEDIA. 
One of the most striking characteristics of the majority of the 
germs from cheese is the feebleness with which they grow on 
ordinary solid culture media. In fact advance in our knowledge 
of the cheese flora is closely associated with improvement in the 
preparation of media for such study. Thus far no one has found a 
medium upon which all of the forms present would develop satis- 
