718 Forestry Quarterly 



to survive in the interior of the crown, the ready loss of lower 

 branches, etc., are signs of intolerance. For more detail we 

 would advise the author, as he is interested in the subject, to 

 refer to Gustav Heyer's classical little volume, Das Verhalten der 

 Waldbdume zu Licht und Schatten, which for the first time systema- 

 matically developed the theory, and on which is built up the whole 

 philosophy of our silvicultural methods. 



Until disproved, foresters will be well advised not to give up 

 their notions of light influence. The only notable attempt to 

 disprove it was made by a forester, Fricke, who believed to have 

 demonstrated root competition to be responsible for what was 

 charged to light influence. {See F. Q., vol. II, pp. 226-30, where 

 also our comment is to be found.) 



The author cites the work of various investigators to determine, 

 with more precision than general observation can ever expect to 

 attain, the question of light required. He details his own work 

 on the same lines and comes to the conclusion that "a study 

 of the foregoing tables soon convinces one that the present methods 

 of determining light values in the forest are unsatisfactory. Too 

 little attention has been paid to the fact that the so-called shade 

 is a discontinuous shade and a constantly changing factor. The 

 variations in light intensity due to clouds, the impossibility of 

 making equal exposures in repeated readings, the variability of 

 the forest cover thus requiring the operator to choose a 'typical 

 station for the forest under consideration, ' and the habit of read- 

 ing only on bright days about noon ; all these make for inaccuracy 

 and emphasize the difficulty, if not impossibility, of determining 

 the relation of forest trees to light by a ' study in the forests. ' " 



The method the author has started on, to secure a controllable 

 shade condition consists (if we understand it correctly — ^it is not 

 very clearly described) of a series of nested frames covered with 

 cheese cloth, and some dyed black, a smaller or larger number being 

 superimposed to vary light intensities, which latter are standard- 

 ized for various combinations by means of a photometer. Under 

 these frames seedlings are grown. The only trouble is, which 

 the author recognizes in a footnote, that these frames have a 

 decided influence upon all other factors of this habitat, and it 

 looks doubtful to us whether it will be possible to control or even 

 measure them. 



The first two bulletins of the series by the author were reviewed 

 in F. Q.. XIII, p. 525. B. E. F. 



