Birds and Forest Vegetation 515 



worked produced ethyl alcohol. It is, of course, true that spontan- 

 eous fermentation of maple sap results in the production of sap- 

 Deer. However, so far as my observation goes, yeast is always 

 added to partially concentrated sap when it is desired to produce 

 this beverage. Some 30 years of observation in the maple-orchards 

 of Vermont lead me to think it is altogether probable that evapora- 

 tion removes the small quantities of alcohol that may be formed 

 too rapidly to permit of any appreciable percentage in the rather 

 small quantities of sap which may be found in crevices. 



"Analyses of decomposing sap show that the sucrose content is 

 considerably diminished as the decomposition becomes pronounced. 

 Invert sugars increase in quantity and are, of course, further de- 

 composed or consumed by the continued growth of moulds and 

 bacteria. I would not care to hazard a guess as to whether the 

 peculiar behavior of sapsuckers who have partaken of fermented 

 maple sap is the result of the beverage or any of its component 

 parts. Personally, I have never seen the indications of intoxication. 

 There may be something in your suggestion that sapsuckers fed 

 upon sucrose contract a sort of diabetes resulting in their death. Of 

 this, however, I know nothing." 



Mr. C. W. Carpenter, also of the Bureau of Plant Industry, U. S. 

 Dept. of Agriculture, who has also made a special study of the fer- 

 menting sap of the sugar maple, says, in a letter dated Feb. 28, 

 1916 : " I recall no determination of alcohol produced in maple sap 

 through the action of microorganisms. Although the sucrose is 

 inverted to some extent through the action of microorganisms, and 

 the content of invert sugar ordinarily is increased as the sap spoils, 

 I am not in a position to say how much, if any ethyl alcohol is 

 produced. Theoretically it would not be very much from a 3 per 

 cent sugar solution. Such small amounts as were produced conceiv- 

 ably would evaporate or be continually diluted by the inflowing sap, 

 as there are no places on trees where a large amount of sap could 

 accumulate and remain for any length of time. I have never seen 

 the reference to sapsuckers becoming drunk after imbibing such 

 fermented sap. I believe it more likely that if this happens it is a 

 case of autointoxication and not over indulgence in alcohol." 



Dr. A. Hugh Bryan, formerly of the Bureau of Chemistry of 

 the U. S. Department of Agriculture and now Supervising Chemist 

 with Arbuckle Brothers of New York, writes me as follows in a 

 letter dated March 28, 1916: " The sap of the maple tree contains 

 anywhere from 0.5 to 3 per cent of sugars, and during the manu- 

 facturing season these sugars are principally sucrose. It might be 

 possible that there is a fermentation on warm days of sap that 

 exudes through the bark with the production of alcohol. It is noted 

 that the sap sours very easily, although I have not seen any refer- 

 ences to the production of alcohol, bv this souring." Still further 

 information has been received from Dr. C. S. Hudson, Chemist in 

 Charge of the Carbohydrate Laboratory of the Bureau of Chemistry 

 of the U. S. Department of Agriculture, in a letter dated March 31, 

 1916: "With regard to the formation of alcohol from maple sap, 



