ABSTRACTS OF REPORTS OF FOREIGN INVESTIGATIONS. 



The distribution of starch in trees during winter, E. Mer 



{Coinpt. rend., is'Jl, pp. !J(iI-!J07; Centralhl. f. a<jr. Chciti., ;^0, Jji!>J, pp. 

 515-547). — The author studied the di.stributiou of starch in different 

 kinds of trees diirini;' the nH)nths from October to April, and found it to 

 he far from constant daring- this time. In the mitUUe of October lie 

 found starch abundant in the bark as well as the bast and xylem. A 

 month Inter it had nciirly all disap[»eared from the bark and bast of the 

 brandies and ui)i)er part of the tree; and the amount in the xylem, while 

 ditfering- with the kind of tree, Avas in all cases less than in summer. The 

 resorption of starch went on steadily for a month or two, when it was 

 nearly completed. This condition remaijied without change until early 

 in JVIarch, when the starch granules first appeared in the green bark of 

 the branches, then in the bast, and subsetiuently in the xylem of the 

 upi)er portion of the tree. It appeared later in the bast and xylem of 

 the middle i^ortion of the tree, and last of all in the roots. By the end 

 of April, before the buds had commenced to develop, apparently about 

 the same quantity of starch had been stored up in the tissues of the 

 plant as had been there the September previous. 



This resorption of starch seems to the author to depend on the respi- 

 ration in the xylem tissue, commencing at the time the leaves begin 

 to lost^ their j^ower of assimilation and continuing up to the beginning 

 of the dormant stage of winter. In support of this theory he cites the 

 following results of experiments with different kinds of woody plants: 



(1) In beach trees from .which the branches and roots had been 

 removed in x^ugust, the starch had fully disappeared by October. 

 Branches of fir from which the leaves had been removed, when kept 

 in a room, lost in 2 months the entire amount of starch which they had 

 previously contained. 



(2) Oak, beach, fir, and pine trees were girdled in June some 25 feet 

 above ground. The starch rapidly disappeared from all the tissues in 

 that part of the tree below the girdle, the degree of rapidity of this 

 disappearance varying with the different trees. 



(3) Young oak and beach branches freed from all leaves and buds, 



when kept in water away from the light, lost their starch in one case 



after 2 and in others after 3 months. 



417 



