182 NATURAL SCIENCE [September 
operations which take place in the leaf are of a comparatively simple 
character. Before, however, we proceed further, it will be advisable 
and indeed highly requisite to provide a table after Mesnard (slightly 
altered) :— 
Products of assimilation. Products of de-assimilation. 
Free fatty oil. Tannoid compounds (rutin, etc.). 
Carbohydrates (starch, glucose, Resins, balsams, and essential oils. 
. etc.). Tannins. 
Albuminoid matters of reserve. Coloured pigments. 
It would be superfluous to adduce facts as bases for arguments 
to prove that the sketch here set forth is a positive and veritable 
representation of what actually comes to pass in the chemistry of 
the living foliar organ. No one disputes that fats, carbohydrates, 
and albuminoids are direct products of assimilation. The fat oil is 
deposited in the cells without there being a simultaneous deposit of 
albuminoid matters; but that there is some close connection 
between the oil and the starch and sugar is evident (though only 
provisionally and superficially) from the respective distribution of 
these bodies in the plant tissues. Thus the oil of the ripe seed is, 
according to Sachs, produced from the starch and sugar transported 
from the primary stem. The storing up of oil occurs in all the 
amylaceous tissues. In the autumn the starch contained in the 
branches of our forest trees is gradually ‘ transformed’ into oil, and 
in the spring this oil is again ‘transformed’ into starch and sugar. 
The cells of the leaf which are free from oil are also free from 
starch. On the other hand, the fact that oil occurs stored up in 
the cells of the perisperms or of the cotyledons of certain seeds in 
Cruciferae, poppies, flax, almonds, ete., in which little or no starch 
is produced, would seem to show that oil and starch are more or less 
independent of each other. “In all cases,” says Mr Mesnard, “ the 
fatty oil is independent of the starch and the glucose, even in the 
rare cases of grass seeds where the oil is specially localised.” I 
think it by no means follows because, as in the winter boughs of our 
forest trees, the oil steps into the place of the vanishing starch, and 
vice versa in the spring, that therefore one of these bodies is un- 
questionably derived from, transmuted into, or even formed at the 
expense of the other. Protoplasmic activity specifically directed is 
amply capable of creating or of destroying one or the other con- 
stituent independently and in accordance with the contemporary 
needs of the organism. Possibly may it not be that the winter 
production of oil is associated with low vitality, while the summer 
production of starch is associated with a high vitality? With regard 
to the organic acids of the leaf, I adhere to the views of Dehérain 
and others that they are oxidation products of the carbo-hydrates, 
and have got nothing to do with the synthesis of the proteids. 
