BOTANY. 853 



The author reviews the history of plienacetin, describes the methods of manii- 

 factiuv, jiivirf tlie munerous physical and chemical tei^ts which have l)een employed 

 in the examination of this snbstance, reports the resnlts of an examination of 9 com- 

 mercial samples!, of which 1 was fonnd to be adulterated with acetanilid, and comments 

 on commerce in plienacetin. 



BOTANY. 



The maple sap flow, C. H. Jones, A. W. Edson, and W. J. Morse ( Vermont Sta. 

 Bal. 10.1, pp. 43-1S4, pis. 17, fills. ^).— This bulletin gives the results of an extended 

 series of observations on the cause of maple saj) flow, the various factors influencing 

 it, and some of the problems of the sugar orchard. 



The investigations were begun in the winter of 189(5-97 (E. S. R., 11, p. 318). The 

 work has been carried on from season to season, and in the present bulletin the 

 results of the continued observations are given. Two phases of the general subject 

 were studied, the physiological and the chemical. The work was carried only to 

 the collection of the sap, the commercial features of the industry having been inten- 

 tionally omitted. A review is given of the general structure and physiology of the 

 maple tree, and attempts are made to account for the presence of tlie sugar, the 

 causes of sap flow, and the relation of various internal and external factors to the 

 flow of the sap. 



Among the possil)le explanations of sap flow are considered sap pressure, move- 

 ment, and bleeding. Gas pressure seems to exert a considerable effect on the flow 

 of maple sap, but the authors state that the sudden cessation of sap flow at the end 

 of the sugar season when there are not only wide temperature variations but also 

 the highest water content, are strong arguments against a purely physical explana- 

 tion of sap flow. It is believed that most of the phenomena of sap pressure and 

 flow are due to the inherent activities of the living cells. The activity of the pro- 

 toplasm is known to vary quickly and widely in response to physical and chemical 

 changes, and alterations in temperature may influence the protoplasmic activity 

 directly or indirectly through the disturbance of the gas tension and the resultant 

 sap movement. A marked fluctuation in the sap flow was noted, a suction-like 

 motion following a strong sap flow. This is attributed in a great degree to tempera- 

 ture changes, the suction being due possibly to the reabsorption of the bleeding cells 

 of the sap exuded by them into the adjacent cells. The comoosition of the sap was 

 found to be somewhat variable from day to day and even from hour to houi'. 



Among the problems of the sugar orchard considered are the location and con- 

 formation of the trees in relation to sugar production, the location of the tap holes, 

 variations in quantity and quality of sap, etc. It was found that maple trees well 

 exposed to sunlight gave more and richer sap than those grown in crowdeil, shaded 

 situations. The quantity of sap obtained from a tree averaged slightly higher on the 

 side bearing the largest and most numerous branches, although indiviilual trees 

 varied in this particular. Almost without exception the largest yields of sap and 

 sugar were derived from the tissues nearest the bark. Fully four-fifths of the sugar 

 was obtained irora a 3-inch boring in large first-growth trees, or from 1 to 1.5 in. in 

 smaller second-growth trees. 



Considering the yield of the entire season, little advantage is likely to arise from 

 too carefully adjusting the points of tapping to the points of the compass. On 

 typical sap days a southern exposure as a rule yielded the most saji and sugar, but 

 on cloudy days the outcome was more uniform between the different points. As a 

 rule, the larger the hole the greater the yield of sap or sugar, but for obvious reasons 

 it is not desirable to wound the tree to such an extent, and tapping the tree with a 

 bit of three-eighths to five-eighths inch is recommended. The maximum flow of sap 

 generally occurred between 9 and 12 o'clock noon. After this time there was a 



