Micro-organism 6i Maple Sap ;i; 



the season but that it becomes more serious as the spring ad- 

 vances. In the case of tree number 3, however, there is a 

 gradual, constant increase in the infection from the very first. 



INFLUENCE OF THE CONTAINER ON THE BACTERIAL FLORA 



The influence of the container upon the bacterial flora < f 

 sap is strikingly illustrated by the following experiment. ( >n 

 March 22, 1910, the sap which had flowed from the 6 trees men- 

 tioned in the previous table during parts of March 21 and 22. 

 was mixed together and plated. The number of organisms per 

 cc. upon nutrient agar was 120, on synthetic agar, 140. Most 

 of these were of the type characteristic of tree 3 as noted above 

 On the morning- of March 23, old but sound wooden buckets 

 previously used in the orchard were thoroughly washed and 

 hung at the 6 trees. The sap was collected, mixed and plated on 

 the afternoon of the next day. The counts on nutrient agar 

 averaged 6,500,000, and on synthetic agar, 500,000. The temper- 

 ature and general weather conditions during the four days 

 covered by this experiment were essentially similar. That this 

 increase of organisms was due to the buckets employed may 

 be seen by reference to the bacterial count given in table 5 for 

 March 25, when clean tin buckets were again employed. While 

 the evidence goes to show that the initial infection from the tap- 

 hole of tree 3 was greater on March 23 and 24 than on March 

 21 and 22, there is no indication that this was the case with the 

 other trees. It should also be noted that the plates poured 

 on March 24 contained no large proportion of colonies char- 

 acteristic of the organism of tree 3, and that the quality of sirup 

 obtained (number 67 page 27 2 ) was n °t characteristic of the 

 organism in question: hence it would seem that the container 

 must be regarded as the chief source of the increase. See Plates 

 VI and VII. 



GENERAL PLAN OF FIELD EXPERIMENTS 



Having established the fact that large numbers of bacteria 

 and other micro-organisms are constantly associated with spoiled 



