236 Forestry Quarterly. 



Fabricius^ investigated the varying starch and fat contents of 

 all parts of the Norway Spruce. The numerous transformations 

 as told by Fisher, Fabricius claims,, hold good for young stems 

 only. In older stems, he finds starch remaining in large quan- 

 tities in winter in both phloem and xylem. Only once in the year 

 is starch wholly transformed into fat, and that is in summer, 

 after the buds begin to unfold. Fat remains in the wood 

 through summer, and is converted back to sugar from September 

 to November. A solution of starch in April takes place only in 

 young twigs ; and a new deposit of starch in summer takes place 

 only in the phloem. In the xylem, the starch in summer is con- 

 verted over into fat, which persists all summer. Roots elongate 

 in June, July and again in October, and while they are elongating, 

 fat is always present in the cortex of the root. 



More recently Sablon^ has published a second paper on the 

 reserves of trees, in which he maintains his position that sugar 

 and fat are of but minor importance as reserve material, reserve 

 cellulose being far greater in quantity than both combined. The 

 maximum of carbohydrate reserves falls at different times for 

 trees with deciduous leaves and those with persistent leaves ; for 

 the former, the maximum is at the fall of the leaf in autumn ; for 

 the latter, at the beginning of activity in spring. For both kinds 

 of trees, the minimum is later in spring. 



In all of the foregoing work there was little attention paid to 



the condition of the carbohydrates in roots, except that Russow 



and Sablon extended their observations to these members. 



Petersen^, however, in two papers gave the results of his exami- 



Nogle Undersogelser over Traeernes Rodliv (with French Resume) 

 Ibid. 1898, I. _ 



nation of the roots of eight species of trees, according to which 



the starch in general was not dissolved in the roots in winter, 



though it did disappear from both phloem and xylem of the root 



of Betula verrucoca and from the phloem of the root of Acer 



pseudoplatanus in December. Petersen's studies extended to the 



stem of a larger number of trees, but, as his results generally agree 



with Fischer's, we need not dwell longer on the details. 



^Untersuchungen iiber den Starke — und Fettgehalt der Fichte auf der 

 oberbayerischen Hochebene, 1905. Abstract Bot. Centrblt. 102, 1906, 29. 



''Recherches physiologiques sur les Materes des Reserves des Arbres II. 

 Rev. gen. Bot. XVIII, 1906, 5. 



'Stivelsen hos vore Lovtraeer under Vinterhvilen. Oversight kong. 

 Danske Vidensk. Selskab Forh. 1896, 50. 



