
838 STORRS AGRICULTURAL EXPERIMENT STATION. 
compared with one another and will at the same time indicate 
the extent of the error of this method of analysis. Hach of 
the columins represents the analysis of the same sample of milk, 
and since the results are given in percentages, the columns 
would agree if the results were strictly accurate. The varia- 
tions in the numbers in the respective columns represent the 
errors of the methods of analysis. 
TABLE 14. 
Comparison of culture media. Figures tndicate percentages. 


CUSTARD GEL- PEPTONE GEL- 
WHEY GELATIN. 




ATIN. ATIN. 
i S fe be a S 
(S) 1S] 1S] (S) 1S) 1S) 
q q <x q <q a 
SS S & SS SR ss 
° Yo) ° Tp) ° Ye) 
Total; - II,700 | 12,900 |12,150 | 13,200 | 17,700 | 14,850 
Slow liquefiers (Group ‘VI. ), 9.6 ope otinm Ud Bt Tom 14.1 TS.a0 
Small lobed (Micrococcus), aa — — 256 a = 
No. 222 (Group WIT), ss Fors geen ea 18.6 [li glee 
Group IV., - - - | 39.9 35.1 35.5 eng 56.2 47.5 
Group IL., - - - - — — ae 4.1 — — 
Group. ls) - - . - 730) 5.7 L267 256 5.3 5:0 
Group V., 202 Hig oe) 9.1 15.5 9.9 8.2 
Rapid ligneners (Group VI. ), 1.5 ere = — — — 
Group IIL., - — 1.0 — 1.0 ae — 
Miscellaneous, No. I, - Bone CF Sey 250 ay re 
Miscellaneous, No. 2, _ 2'32 f7eL — — I.0 
Miscellaneous, No. 3, -| ~— : ToT 220) — =— 
Miscellaneous, No. 7, - — LEAS, — —— — a 
Miscellaneous, No. 8, - — — — — — 6.0 
Undetermined, - z : — — — — te, 6.0 




From this table it would appear that while peptone gelatin’ 
gave sometimes the larger bacteria count, it does not give as 
good a differentiation as either of those made from milk. ‘This 
is shown chiefly by Group IV., which is decidedly larger with 
the peptone gelatin than with the other two. The Group IV. 
is a neutral group and will always increase in percentage as 
the differentiation of other groups becomes less sharp. Many 
of the acid bacteria of Groups I. and V. are evidently counted 
with Group IV. in the peptone gelatin plates. The only other 
considerable difference in the three media is in the percentage 
of Group V., which was much higher in the custard gelatin. 
But since our other experiments (see Tables 15 and 16) _ 

