H. BOTANY AND HORTICULTURE. 



361 



a heat of 158 Fahr. ; while in willows, for instance, the germ 

 of the seed is killed by simple exposure to the sun. 28 A^ 

 3Iarch^l8l2. 



MOVEMENT OF THE SAP IN PLANTS. 



The latest views in reoard to the still somewhat obscure 



CD 



subject of the motion of sap in plants are given by W. K. 

 M'Xab, of the Royal College, Dublin, in a recent number of 

 the Garden. Two distinct currents exist, a slow and a rapid. 

 The rapid current relates exclusively to the process of trans- 

 piration, varying, therefore, with the season and the time of 

 day. It takes place in the day-time, during sunlight, and the, 

 fluid passes up in the xcalh of the wood-cells of the fibro- 

 vascular bundles. The slow movement is connected with the 

 transport of assimilated matters from one part of the plant 

 to another, chiefly from the leaves to the growing points of 

 stems and roots, or wherever cell multiplication or cell en- 

 largement is going on. It is quite irregular, may move in 

 any direction, depends on osmose chiefly, and is a true move- 

 ment from cell to cell. The rapidity of the first current, as 

 calculated by Sachs, was 23 centimeters (nearly 10 inches) per 

 hour in the silver poplar. M'Nab observed a rate of from 

 42 to 46 centimeters per hour in October, and considers that 

 this would have been doubled in June. Of the total water 

 present in the cherry laurel (63 per cent, of its entire weight), 

 he regards 6 or 7 per cent, only as water of transj^iration. 

 The Garden, 1813,115. 



CINCHONA IN JAMAICA. 



It is well known that the various species of cinchona-trees, 

 when transplanted from their native region in South America, 

 although retaining their botanical characteristics, do not al- 

 ways furnish the same quantity and quality of alkaloid, this 

 being influenced by latitude, moisture, and other conditions. 

 A recent examination of cinchona bark from trees growing 

 in Jamaica has, however, proved very satisfactory, the total 

 amount of alkaloid obtained being considered reasonably large, 

 and likely to improve with the age of the trees. The Cincho7ia 

 calasaya is the most promising, exhibiting a percentage of 

 quinine of great economical importance. In this respect it 

 had a decided superiority over the same plants cultivated in 



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