EXPERIMENT STATION REPORTS. 143 



exudate on the thoracic side opposite the abscess and there were ad- 

 hesions of parietal to visceral pleura at this point; heart showed very 

 extensive subendocardial hemorrhage, especially in the left ventricle. 

 There was only a slight congestion of the nasal mucosa and cranial 

 sinuses. 



A microscopic examination showed a very short, rod-shaped organism 

 in the pus from the abscess, but nothing in the blood or other tissues 

 of the body. We concluded that the i^rimary lesions was caused by the 

 infected puncture of the reticulum by the tack. This may have taken 

 place some time before the generalized infection or intoxication. 



PICKLE INVESTIGATION. 



Dr. Otto Rahn of this Department has been interested, in conjunction 

 with Prof. Frank Kedzie, in endeavoring to ascertain the cause under- 

 lying a fermentation difficulty encountered by pickling stations. Heavy 

 losses have been sustained by the pickling industry not only in Michi- 

 gan, but elsewhere. Because of an inability to secure cucumbers, further 

 work has been delayed till August of this year. 



SUMMARY OF SOME EXPERIENCES IN THIS LABORATORY. 



Some experiences relevant to the determination of the Bacterial Con- 

 tent of Milk. 



For the past three or four years, considerable work has been done in 

 the Bacteriological Laboratory of the Michigan Agricultural College, 

 having a direct bearing upon the interpretation of the bacterial con- 

 tent of milk. Last year, special systematic work was inaugurated at 

 the instigation of the "Committee on Standard Methods of Bacterial 

 Milk Analysis," of the American Public Health Association. 



Those of our Laboratory who have contributed to this work, are, Mr. 

 Sayer, Mr. Rahn, Miss Farrand, and Miss Northrup, all equally re- 

 sponsible with myself for these experiences. 



Our purpose in presenting this paper relates both to the analytical 

 significance and also to the suggestiveness of the work so far as future 

 progress is concerned. 



Our work from which these experiences are drawn may be divided into 

 three distinct lines of investigations. (1) "The Associative Studies." 

 (2) "The Keeping Qualities of Butter." (3) "The Systematic Work" 

 conducted for the committee named above. 



In the "Associative Studies" it was our privilege to follow the de- 

 velopment of micro-organisms in fresh milk through to the point of 

 loppering. From time to time, throughout the period from milking to 

 the loppering of the milk, plates were made of the samples for the pur- 

 pose of an intimate study of the micro-organisms present at the differ 

 ent stages, and of an estimate of the rapidity of their development. 

 This study, which involved an enormous amount of repetition, revealed 

 to us that the germ content of milk varies with each stage of its de- 

 velopment to the time of loppering; accordingly, the micro-organisms 

 present in milk when fresh may not be the same micro-organisms 

 present six hours, twelve hours, or twenty-four hours after milking. 



The following table taken from our work on "Bacterial Associations 

 in the Souring of Milk" illustrates this thought. 



