Grossenbacher Radial Growth in Trees. 13 



decrease in the carbohydrates occurred until the end of the 

 stem's life. 



The observations by Fabricius 27 on the distribution of food in 

 large spruce trees throughout the entire year seems also to throw 

 some light on the possible relation this may have to the inception 

 of radial growth in spring. The first tree was cut in February. 

 It was 25 m. high, had 68 growth rings at the base and its low- 

 est branches were 14 m. above the ground. The bark of the 

 stem 30 cm. above ground had considerable starch in the medul- 

 lary rays, and less in the parenchyma. The older phelloderm 

 and ray cells contained less starch than the younger ones. Prac- 

 tically the same distribution of starch obtained in the entire bark 

 of the trunk up to the first branches. From the branches up- 

 ward the starch gradually increased to a maximum at 21 m. and 

 diminished again near the distal tip where but little was present. 

 The twenty-five outer rings in the lower part of tiie trunk had 

 live, starch-bearing wood-rays and gum-canal cells and only the 

 outer half of the youngest wood-ring contained no starch. Fif- 

 teen meters above ground where the stem had 36 rings only 19 

 contained live cells and at 18 m. about a tenth of the ray cells 

 were alive and starch bearing in the innermost of the 21 rings. 

 In the one-year shoot only about half of the pith contained starch. 

 The distribution of the fats was similar to that of the starch but 

 it was much less in amount except in the youngest twigs. The 

 decrease of reserve food near the distal portions was thought to 

 be due to a loss through respiration during winter. 



The starch content of small roots was slight but usually in- 

 creased with their diameter up to 1 to 2 mm. An excentric root 

 having 55 rings on one side and 37 on the other contained starch 

 in the outer 20 rings of the thicker side and in the outer 15 of the 

 thinner. Only the roots over 2.5 cm. in diameter contained fats. 

 In some cases excentric roots were found to have a difference of 

 as much as 50 growth rings between the broad and narrow sides, 

 yet the cambium on the thinner side was normal, although it was 

 evident that it often remained inactive during several years. 

 The relative amounts of starch stored on the different sides of an 

 excentric root was proportional to the amount of growth on any 

 side. 



27 Fabricius, L. Untersuchungen iiber den Starke-und Fettgehalt der 

 Fichte auf der oberbayerischen Hochebene. Naturw. Zeit. Land-u. 

 Forstw. 3:137-76. 1905. 



