652 
Proceedings of Royal Society of Edinburgh. 
On the Vascular System of the Hypocotyl and Embryo 
of Ricinus Communis, L. By Edith Chick, B.Sc., 
Quain Student in Botany, University College, London. 
(With Three Plates.) 
(Read June 19, 1899.) 
Sections of the hypocotyl of Ricinus communis are frequently 
examined as typical of the young stem, in which widely separated 
vascular bundles are ultimately united by a band of interfascicular 
cambium, and this by giving rise to secondary tissues connects 
the xylems and phloems of the primary bundles to form concentric 
continuous rings. 
In the young unthickened hypocotyl of Ricinus there are eight 
such bundles connected by a continuous starch sheath and one 
layer of smaller cells immediately inside it. In some sections, 
however, confusion arises owing to the increase of the number of 
vascular bundles, and in the case of older hypocotyls these extra 
bundles are embedded in the cambium ring and have rather the 
appearance of secondarily formed tissues. 
It was in the first instance to clear up the origin of these bundles 
that, at the suggestion of Professor F. W. Oliver, the following 
work was begun. Afterwards, as there seemed some advantage in 
working out in full the arrangement of the vascular system in this 
plant, which is so frequently used as a dicotyledonous type, it has 
been followed from the root, through the hypocotyl, to the 1st 
and 2nd internodes of the epicotyl. 
The well-developed primary root of the seedling of Ricinis 
communis averages about 2 mm. in diameter. About 5 mm. 
below the junction with the stem it enlarges rapidly to attain the 
diameter of the hypocotyl, which varies between 4 and 5 mm. 
It is from this swollen portion of the root that most of the first 
developed lateral rootlets take their origin. They appear at the 
surface at points corresponding to the position of the proto-xylems 
within, and form four vertical rows corresponding with the tetrarch 
symmetry of the root cylinder. The hypocotyl tapers slightly 
