668 War mg ton .— The Effect of Boric Acid and Borax on 
Agulhon (1 (a)) has put forward the idea that, as the element occurs in com¬ 
paratively large quantities in the wood, it may be of especial importance in 
the formation of the vascular system. This view is supported by the fact 
that a disintegration of the vascular bundles takes place, proceeding from 
the apex downwards, in broad bean plants deprived of boron : this 
anatomical change is at present under investigation and will be described in 
a later paper. 
Another noticeable feature in plants suffering from a deficiency of 
boron is that the injury is first apparent in the meristematic regions. 
Whereas death under normal conditions occurs first in the lower parts of the 
plant, ‘ dying off ’ progresses from the apex and travels downwards, so that the 
activities of boron appear to be closely connected with the healthy develop¬ 
ment of permanent from meristematic tissue. 
The action of boron is presumably of a specific nature, since it appears 
to function in a different manner in different plants, possibly being in 
some cases an essential element, and in others of comparatively little 
importance. 
The relationship of boron to plant life is somewhat suggestive of that 
between vitamines and animals, and in various ways the resemblance 
appears to be very close. The main lines of agreement are : 
1. The comparatively small quantity of the substance required. 
2. The unhealthy condition resulting from a deficiency of the sub¬ 
stance. 
3. The prevention of, or recovery from, the unhealthy condition by the 
addition of the substance. 
4. The need for the supply of the substance to be maintained throughout 
life. 
Accessory food factors or vitamines are utilized in small quantities 
quite out of proportion to the importance of their function, and similarly 
even 1 : 2,5^0,000 boric acid has been shown to be adequate for healthy 
growth of the broad bean. Vitamines are generally regarded as a class 
distinct from the better known animal food-stuffs, and it is conceivable that 
a similar category of accessory plant foods would afford a convenient means 
of classifying such substances as boron. A class of this nature was fore¬ 
shadowed by Agulhon (1 (a)) in his ‘ particulars ’ elements, but he was not 
able to demonstrate a specific case where death resulted from the deficiency 
of such an element. 
The function of boron in the life of the plant is still an unsettled question, 
though it seems more probable that its action is in some way nutritive 
rather than catalytic; similarly it is uncertain whether vitamines ‘ prove to 
be structural components of living tissues of which a supply is essential even 
though quantitatively unimportant, or whether (as it is equally possible) 
