THE EFFECT OF LIGHT ON THE 
GROWTH OF TREES. 
BY S. ARDEN. 
In connection with the cultivation of the Para rubber tree and 
— though to a less extent — coconuts and other tropical products, 
there is perhaps no question upon which opinions are divided to 
such an extent as on that of the correct distance to allow between 
the trees ; for while some prefer to plant the Para rubber tree for 
instance, 36' X36 r (about 33 trees to the acre), others maintain that 
planted io' x 10' (435 trees to the acre) or even 8' x 8' which gives 
680 to the acre will give a larger yield per acre, although prepared 
to admit that the yield per tree will be considerably less when 
planted so closely. 
I have recently had the opportunity of seeing some 20 acres of 3 
year old trees planted 6 / x6'J)ut it seems impossible to believe, 
that a practical planter who plants his coffee shrubs 12' x 12 A— the 
recognized distance on soil of ordinary fertility — -would attempt to 
argue that a Para rubber tree, which, when fully developed has a 
spread of about 36 feet, would under such conditions have anything 
like a fair chance to develop. 
There appears in the current number of the “Indian Forester " 
a review of a valuable book entitled “ Economics of Forestry " 
written recently by Professor FERNOVV, L. L. D., Director of New 
York State College of Forestry, and I have made a few, notes hav- 
ing a direct bearing on the subject, trusting that they will prove 
interesting to those readers of the ‘Agricultural Bulletin 1 who are 
interested in this important question, and who may not have an 
opportunity of studying Dr. Fernow’s book. 
In chapter VI Dr. FERNOW deals with the Natural History of the 
forest, and after observing the influence of temperature, moisture, 
and soil conditions, together with the methods adopted by nature 
for the transportation of the seed, on the natural distribution of the 
various species which form the particular type of forest met with 
in passing from the Tropics to the Northern Latitudes, and from 
sea level to the highest altitudes, proceeds to show that “not only 
is the composition of the forest largely a result of changes in light 
conditions, but the actual amount of production is a function of the 
light, for the annual production of wood is in direct relation with 
the amount of foliage which the tree can exhibit to the influence of 
light . 
This is a very definite statement, emphasizing a well known 
scientific fact as to the important part played by sunlight, in the 
elaboration of the sap which is destined to form not only the 
wood but the leaves, fruit, latices and other parts of the tree. 
The whole art of forestry and of agriculture also, is based on 
the laws of accretion. 
An attempt is being ma le in the United States after the manner 
of the German Foresters to determine the volume development of 
