VERMONT AGRICULTURAL REPORT. 6l 



the stubble. The plant also gathers nitrogen from the air through bac- 

 terial agencies. In fact, a clover crop when removed, leaves the soil 

 better than it found it. 



The feed sack, if it contains the right sort of feed, may greatly add to 

 the plant food content of the manure. Cotton seed, linseed and gluten 

 meals, the distillers' grains and the wheat offals are rich in plant food. 

 Such purchases of feed as are made should be made with reference to 

 their service as manure makers. 



The phosphate sack is all right in its place; but much of the purchase 

 is hap-hazard, ill-advised and at exhorbitant prices. The trouble is that 

 farmers often buy low grade goods rather than high grade ones. Low 

 grade goods are almost always the most expensive and the least ser- 

 viceable. 



The chemist's tale is told. It has been a plain one, unillustrated and, 

 perhaps dry. But there are a number of points touching the "big four" 

 of agriculture, nitrogen, phosphoric acid, potash and lime, which he has 

 made, which, if noted and profited by, may add much to the success 

 of him who puts them into practice. 



EXCERPTS FROM EXPERIMENT STATION BULLETINS 



OF 1903. 



THE MAPLE SAP FLOW. 

 The results of several seasons' work in the sugar bush point to the 

 following conclusions as to sundry matters pertaining to the maple sap 

 flow: 



1. Whence comes the sugar? And what relation has the structure of 

 the tree and its life functions to sugar formation? Maple sugar is 

 formed from starch in the late winter and early spring. This starch is 

 stored in certain sap wood during the preceding summer and is probably 

 transformed into sugar through the action of enzymes. The starch is 

 formed in the leaves under the influence of sunlight. A large leaf area 

 and plenty of sunshine conduce to sugar making. The reverse conditions 

 hinder it. 



2. What is the cause of the sap flow? The immediate cause of the 

 flow from the tap hole is sap movement under pressure towards the 

 point of least resistance. The exciting cause of this flow seems to be 

 temperature fluctuations back and forth over the 32 degrees F. line, 

 causing alternation of pressure and suction, a pumplike action. The 

 ultimate and absolute cause can hardly be this or any other physical one. 

 It probably is a function of the living cell. 



3. What relations to the sap flow are borne by weather changes, the 

 water and gas contents of the tree, pressure and suction, and direction of 

 sap movement? The maple trunk rapidly accumulates water during the 

 late winter and early spring. It at all times contains much gas enclosed 

 within the cell walls of the woody tissues. The sap passes through 

 these walls readily; gas, scarcely at all. Moreover, temperature changes 



