PART T 



MICRO-ORGANISMS OCCURRING IN MAPLE SAP AM) THEIR IN- 

 FLUENCE ON THE COLOR, FLAYOH AM) CHEMICAL 

 COMPOSITION OF SMUT 



By H. A. Edson 



I NTRODUCTION 



A preliminary contribution upon the work presented in this 

 paper appeared in bulletin 151 (1910). Only the more important 

 facts reported at that time are restated in the present paper, but 

 quotations and repetitions stripped of details are introduced when 

 essential to a clear and complete presentation. The problem is 

 most satisfactorily introduced, however, by a somewhat lengthy 

 quotation from the former paper, in which, for the information 

 of any who may not be familiar with them, are included brief 

 descriptions of the main facts of sap flow and of sugar making" as 

 practiced in Vermont. 



"Late in March, in this section, evidences of coming spring- 

 appear. The nights are still cold and frosty but the days are 

 genial and the temperature rises a few degrees above the freez- 

 ing point. If, at this time, the trunk or limbs of certain species 

 of the genus Acer are fresh wounded a sweet sap exudes. The In- 

 dians were familiar with this phenomenon before white men 

 came ; and had learned to collect, to concentrate and to make 

 sugar from this sap. The early settlers 1 learned from them the 

 essential steps which, in modified form, constitute the procedure 

 followed in the maple sugar industry today." 



"According to modern practice the tree is tapped by boring 

 a half-inch hole 2 inches deep about 4 feet from the ground. A 

 round, hollow spout or "spile" of wood or metal, upon which 

 is suspended a bucket to catch the dripping sap, is driven into 

 the hole. The sap flow is not continuous but is divided into 

 short intermittent periods, technically termed 'runs.' It oc- 

 curs only during the three or four weeks which immediately 

 precede the unfolding of the leaf buds. Both its periodicity and 



1 Garden and Forest 4, p. 171. 



