344 Bulletin 167 



sap, it remained to determine the influence (if these agents upon 

 the quality of sirup. Several hundred pure cultures of the pre- 

 dominant organisms occurring in various types of spoiled sap 

 were isolated and studied more or less critically. After their 

 character had been roughly determined, certain ones were se- 

 lected for the inoculation experiments to be described presentlv. 



The Orange county sugar orchard in which the field ex- 

 periments were carried out is situated upon a western slope 

 but is exposed to north winds. The soil of the greater part of the 

 place is wet. and the orchard lias had the reputation of producing 

 a grade of sirup of only medium standard both in flavor and 

 color. See Plate I. 



The g'eneral plan followed during the first season was to 

 secure sap as free from bacteria as was feasible without steriliza- 

 tion, and to introduce a sufficiently heavy inoculation of the 

 specific organism to produce an overgrowth of the introduced 

 species. In some of the later series pasteurization was employed 

 before inoculation, and during the last season fractional steriliza- 

 tion was attempted. Following inoculation, after a period of 

 incubation, the saps were concentrated to sirups under uniform 

 conditions. The sirups were placed in glass jars, sterilized, 

 sealed and shipped to the station bacteriological laboratory at 

 Burlington, where they were stored in the dark for later scoring 

 as to color and flavor, and subjected to a complete chemical 

 analysis. As suggested above, the details of handling the sap 

 before and during incubation varied somewhat from time to 

 time. The details of these variations will lie explained with the 

 discussion of the individual samples. 



In addition to the inoculation experiments referred to, which 

 were usually confined to the early runs of the season, an attempt 

 was made to procure late run sap relatively free from infection. 

 in order to compare it with material drawn at the same time 

 from the same trees under ordinary conditions. For this pur- 

 pose trees which had begun to run sour were selected and. with- 

 out disturbing the original tap-hole, spile or bucket, another spout 



