788 JOURNAL OF FORESTRY 



That the visible smelter smoke, contrary to common belief, is "little 

 to be feared as an actual instrument of damage to vegetation" may be 

 open to question, at least it is apt to contain the injurious poison, yet 

 for psychological reasons it might be best to secure clearance. 



There is no practical result from the findings discussed except in this 

 one sentence: "Our investigation and the temperature curves (in the 

 stacks) . . . have shown us that where there is fume injury the 

 answer to the problem is in hot gases, gas dilution, and high stacks." 



The History and Legal Phases of the Smoke Problem. Bulletin of the Amer- 

 ican Institute of Mining Engineers, May, 1917, pp. 893-906. 



Coventry discusses the light and soil require- 

 Light and Soil ments of different Indian species in natural re- 

 in generation and makes some general observations 

 Natural which are worth noting. 

 Regeneration On the plains the light conditions on the soil 

 are dependent on the density of the canopy alone, 

 but on hills, for places of the same elevation, the influence of aspect 

 and gradient has also to be taken into consideration; light conditions 

 on a northern aspect under an open canopy may be similar to those 

 under a denser canopy on a southern aspect. For practical purposes 

 the author distinguishes three conditions of light : 



(i) Maximum light conditions — i. e., where the soil is entirely un- 

 protected from direct sunlight. 



(2) Moderate shade conditions — i. e., where the soil is partially pro- 

 tected either by a light canopy of vegetation, or by the aspect, or by the 

 combined influence of both the vegetation and the aspect. 



(3) Heavy shade conditions — i. e., where the soil is more or less 

 completely protected, either by a dense canopy of vegetation, or by the 

 aspect, or by the combined influence of both the vegetation and the 

 aspect. 



For the classification of species the author does not use our negative 

 terms — tolerant and intolerant — but the positive terms — "heavy shade 

 demanders, moderate shade demanders, non-shade demanders." 



Shade-demanding species require protection from the sun only dur- 

 ing their early years, for later on they grow perfectly well with full 

 exposure to the sun, but at the same time are adapted to bear more or 

 less shade. They thus gradually lose their shade-demanding character 

 and become simply "shade-bearers" ; but it is important to bear in mind 

 that the term "shade-bearer" implies, in addition to its ordinary mean- 

 ing, that such species are also shade-demanding for the purposes of 

 their natural regeneration. 



