378 BOTANICAL GAZETTE [NOVEMBER 
physiological side of the question to justify a few words in conclu- 
sion. GOEBEL (5, chapter iii), to explain the replacement of the 
terminal by a lateral shoot, offers the theory that the change in 
direction of growth of the lateral comes about because of changed 
conditions of nourishment. He thinks that the main transpiration 
current, which ordinarily goes to the terminal shoot where growth 
is most vigorous, is deflected when the terminal shoot is removed, 
and passes into the uppermost lateral. The great increase in nutri- 
tion acts as a stimulus, causing the lateral shoot to become erect. 
He describes several cases of layering among conifers, and attributes 
the change in direction of growth of the layered branch to the same 
factor. In this case the increased amount of food materials which 
acts as the stimulus is furnished through the agency of the newly 
formed root system. This theory would fit most of the cases of 
layering which have been described, but in one example which came 
under my observation on Isle Royale (no. 4 above) the change of 
direction of growth took place with absolutely no root formation. 
The same is probably true of those described by ScHROTER (11). 
Here are cases, therefore, where GOEBEL’s explanation certainly 
does not hold, and so far as this bit of evidence goes, it throws - 
doubt upon his theory as a whole. 
THE UNIVERSITY OF CHICAGO 
LITERATURE CITED 
1. CHITTENDEN, A. K., Forest conditions of — New Hampshire. 
U.S. Dept. Agric., Been of Forestry, Bull. 55. 1905. 
2. Curist, H., Schweiz. Zeitschr. fiir Forstwesen, seb, p. 2 258 (see VOGTHERR 
13). 
3- CLements, F. E., The life history of lodgepole burn forests. U.S. Dept. 
4. Forest Service, U.S. Dept. Agric., The subalpine fir. Silvical Leaflet 1. 
5- GOEBEL, K., Einleitung in die experimentelle Morphologie der Pflanzen. 
Leipzig u. Berlin. 1908. 
6. Kiaiman, A. O., Pflanzenbiologische — aus Russisch Lappland. 
Acta Soc. Fauna et Flora Fenn. 5: n. 3. 
7- Kunze, G., Einige Falle von Pieiatons dee Nebenaxen in Hauptaxen 
bei den Abilis: Flora 9:145-151. 1851. 
8. Loupon, J. C., Arboretum et Fruticetum Britannicum. London. 1844- 
