THE COURSE TAKEN BY FOOD MATERIAL 
FROM 
LEAVES TO DIFFERENT PARTS OF THE STEM, 
By IsaBeL J. HuNTER. 
(Read 3rd July, 1903.) 
One reads of a German poet who, when asked why he was so 
fond of walking in the fields, replied that he delighted in hearing 
the plants grow. It is not given to every one to have so acute 
a sense of hearing, nor, were other sounds to be heard in 
proportion, would one envy the German his possession. But, 
though denied the poet’s privilege of hearing the plants grow, we 
may be pardoned if we have a not unnatural desire to learn what 
we can about their growth. 
That much is already known goes without saying, but if it were 
not a marked trait of the human character ever to set a higher 
value on what is not known than on what has already been made 
manifest, there would be no such thing as ignorance. 
Therefore I do not purpose to treat of facts already within our 
grasp, but of one which the work of others has brought within 
our reach. I refer to tracing the direction and measuring the 
rate of the food current in plants. 
Botanical research has sufficiently demonstrated that it is 
within the green cells of the leaves that this current has its origin, 
and that it travels by the bast tissue to wherever growth is taking 
place, or food substances are being stored for future use. But 
though many have succeeded by the use of coloured fluids in 
determining the direction taken by the sap ascending from the 
roots, evidently no one has hitherto thought that it might be 
possible to show with equal clearness the direction taken by the 
descending sap. 
The green cells of the leaf are sometimes compared to factories 
to which the raw materials are transported, both those entering 
