Agricultural Research in New Hampshire 33 



grove and the rest in grassland at the edge of the grove. For a time they 

 appeared to be doing well; five developed green tips on the buds, but b\- 

 May 29 all appeared to have died. 



Location of Siveet Trees. Eleven samples of sap were tested for 

 sweetness, four from Dover and seven from Aladbury. Most of them 

 were normal, with between 3 and 4 per cent sugar, but one contained 

 5.6 per cent which is considerably better than the average. As 1945 was 

 not as "s^\eet" a \ear as 1944. further observations may show that this 

 tree is really superior. 



Sap-floiv Studies. The short season of 1945 upset some of the plans 

 for studying characteristics of sap flow. Random observations through 

 the winter indicate that previous conclusions relative to the correlation 

 between weather conditions and sap-flow are probably correct, although 

 there are some instances for \\hich there is no explanation. 



Further investigation is necessary to determine changes in the rate 

 of flow from hour to hour during the da\'. Records indicate that this is 

 largely controlled by temperature, but the data are inadequate to substan- 

 tiate this tentative conclusion. 



Comparison of the total yield of an extra-sweet tree with that of 

 one with sap of normal sweetness was attempted; while the results are 

 not conclusive, they certainly point strongly to the superiority of the 

 extra-sweet tree. Sweet Sue, in the last 19 days of the season (on only 

 11 of \\hich sap ran in any quantity), produced decidedly more sap than 

 did the normal tree, referred to as Plain Jane. The following table sum- 

 marizes the results. (The s\'rup is standard o-rade, 11 pounds to the gal- 

 lon.) 



Yield of Sweet Tree Compared with that of Normal Tree 



On March 15, 1945, a sample of maple sap was exposed to acid analv- 

 sis. It reduced Benedict's Solution, and had a sugar content of 0.706 ac- 

 cording to the polarimeter. It is unlikely that this is the correct sugar 

 content, as there mav be both dextro-rotatorv and levo-rotatorv sugars 

 present. The sample was stored in an ice box, and the pH taken every 

 day. After standing for two weeks, the sap became slightly colloidal. 

 The pH remained quite constant for a period of slightly over a month's 

 time. It then started falling rapidly, until at the end of the experiment 

 it was 3.98, showing that there was something present in the sap which 

 increased the acidity of the solution. The exact reason is not known, 

 but it is probably due to the action of an enzyme. This is believed to be 

 an oxidation process whereby the sugar is converted to acetic acid. 



Selected species of trees were tapped to determine the characteristics 



