162 BOARD OF AGRICULTUEE. 



cultiviitccl under glass during their proper seasons of activity 

 and repose. 



The difficulty often experienced in getting flowers from 

 specimens of cactus and other house-plants by persons who, 

 being ignorant of these facts, carefully water them alike at all 

 times through the year, is thus readily explained. The plants, 

 having no opportunity to ripen their tissues, can never be in 

 condition to blossom. 



After the fall of the leaves and the ripening of the wood 

 and buds, the stem and branches of most trees and shrubs 

 will be found upon examination to be unusually dry and free 

 from sap, and it has been said that this was an indication of 

 hardiness. That most of our indigenous species assume this 

 condition during about one-half of the year is doubtless true, 

 but the presence or absence of sap cannot be considered as con- 

 clusive evidence of tenderness or hardiness. The grape-vine 

 appears quite porous and free from sap in December, but is 

 often winter-killed. On the other hand the sugar and silver- 

 leaved maples are usually full of sap on some days of every 

 month in the 3"ear, and yet are perfectly hardy. 



The curious facts that the Indians used to make maple-sugar 

 in November, that good sap-days may occur during any time 

 between the first of October and the first of May, that the 

 flow of sap varies remarkably during the ordinary sugar sea- 

 son according to the weather, and that the percentage of 

 crystallizable cane-sugar in the sap of the same tree is also 

 subject to extraordinary fluctuations in difierent years and in 

 difierent months of the same season, render the Acer saccha- 

 rinum or sugar-tree of North America, a species of peculiar 

 interest to the inquiring botanist. While we know that every 

 tree of our forests produces a little sugar of some sort at some, 

 period of its growth, usually at germination, at flowering, and 

 in fruit, we have not learned why the maples alone produce 

 cane-sugar in sufficient quantity to render its extraction prof- 

 itable. 



Stimulated by the desire of some further and more definite 

 information upon these points, and by the hope of adding at 

 least a little to the general stock of human knowledije we in- 

 stituted a scries of observation;; at the Massachusetts Ao-ricul- 

 tural College in the spring of the present year, and ayrived 



