168 Rerorr oF tuk CuemicaL DerpartMENT OF TOE 
Mr. L. A. Rogers, Assistant Bacteriologist, has done much of 
the routine work connected with the bacteriological examina- 
tions. Mr. J. A. Le Clere and Mr. A. J. Patten have rendered 
efficient assistance in some of the chemical work. 
II. HISTORICAL OUTLINE. 
The following outline of the work previously done in relation 
to cheese ripening covers only those features that relate to the 
special problems we have been studying. 
In 1887, Benecke,! in discussing the role of bacteria in cheese 
ripening, stated that, while they probably caused such changes, 
yet the ripening might really be due to the activity of Some unor- 
ganized ferment. He pointed out that, if bacteria are not essen- 
tial to cheese ripening, this fact could be made clear by the 
preparation of cheese under conditions which would exclude 
bacterial activity. Acting on this suggestion Adametz? pre- 
pared a number of Hauskdse, a form of soft cheese, in the nor- 
mal way, except that he added various disinfectants to the milk 
or to the curd derived from it. 
When cheese made with the addition of kreolin or of thymole, 
were examined bacteriologically, they were pronounced sterile; 
but even when kept for double the normal length of time, they 
did not take on the appearance of ripened cheese. His experi- 
ments with salicylic acid, oxalic acid and with vapors of carbon 
disulphide and iodine were less satisfactory in repressing the 
microérganisms in the cheese, but these agents seemed to hold 
back the ripening in proportion as they inhibited the activity of 
germ life. | 
Cheese investigators quite generally accepted these results as 
settling the point raised by Benecke, and during the succeeding 
ten years the work on cheese ripening was based upon the 
theory of germ action. 
The phenomena of ripening in cheese may be divided into two 
classes, (1) the chemical decomposition of casein and (2) the for- 

41Benecke. Cent. f. Bak., I Abt., 1:521 (1887). 
*Adametz. Thiel’s Landwirtschaftliche Jahrb., 18:227 (1889). 
