FOREWORD 



The spoilage of foods may be due to physical, chemical or biological causes . 

 The last named is generally known to be the most common and serious cause, 

 and microorganisms are admitted to be the usual biological factors involved. 

 A common type of spoilage in canned foods, called flat sours, results in an 

 increased acidity of the contents of the can with not enough internal pressure 

 to cause bulging of the ends. No extensive bacteriological study of flat sours 

 had been made at the time of undertaking the work reported in this bulletin. 



In the course of the studies an extremely interesting and unusual organism 

 was encountered. Part I deals with a description of this organism as re- 

 ported by Mrs. Wyant, formerly Research Associate in this Section. Part 

 II is the record of an attempt to discover the organism or organisms respon- 

 sible for flat sours. Mrs. Wyant was assisted in her efforts by two students, 

 Miss Rhea East and Miss Esther Severance. Mr. Tweed, who has suc- 

 ceeded Mrs. Wyant in charge of investigations into food bacteriology was 

 assisted by an advanced student, Miss Lucile Roach. They have made a 



valuable contribution to the subject. 



WARD GILTNER. 



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