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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
young for such a diet, on farinaceous food. The deformity — 
swollen wrists and beaded ribs — is the result of improper food, 
but it is not an adaptative phenomenon, the deformity is not in any 
way fitted to remove the cause of the disease. But in the case 
of etiolation, I believe that the deformity is specially adapted to 
give the plant the best chance of escaping the cause of the evil, 
namely, darkness. 
In attacking the problem, the most obvious point to be con- 
sidered is the mode in which darkness normally enters into the 
life of a green plant. From our present point of view the dark- 
ness of night may be neglected, and only those circumstances 
considered which produce darkness of long duration. The sim- 
plest cases are those in which shoots develop underground — for 
instance, from the subterranean tuber of a potato. An eye 
developes into a shoot, bearing small leaves, which do not attain 
their full size until they reach the light. If the flower-pot con- 
taining the potato is placed in a dark room, the shoot, on emerg- 
ing from the soil, will continue to grow, under the influence of 
darkness, as though it were still under ground. So that in 
becoming a typical etiolated shoot, it simply continues the 
normal underground habit, of which the growth of internodes 
rather than of leaves is the characteristic. The same thing is 
true of a seed [e.g. a bean) planted in the ground : its plumule 
behaves like the potato shoot, and if kept in a dark room, it con- 
tinues to grow in the air as though it were still under ground. 
The characteristic feature in the case is that the whole 
energy of growth is thrown into elongation of internode, the pro- 
duction of leaf being in abeyance. This is clearly a useful dis- 
tribution of growth ; for if the shoot never emerges into light its 
leaves are useless : it will be time enough to grow leaves when 
there is a chance of making use of them. And the only chance 
of reaching the dayliglit, on which the activity of the leaves 
depends, is that all available strength should be devoted to the 
elongation of the stem on which the leaves arc carried. God- 
lewski made a Phaseolus grow through a darkened tube of such 
length that, wlicn at last the shoot was allowed to reach the 
light, it was so much exliaustcd that it never thoroughly 
recovered. But to reach the light at any cost was its one 
chance of escaping certain death, and for such an end the 
deformity of etiolation is well fitted. It should be especially 
