1 56 Barber . — On the Nature and Developmejit of the 
in the manufacture of walking-sticks ; while the hard 
pyramidal masses are broken off the ‘ knobwood ’ of South 
Africa to serve as playthings for the children 1 . 
These structures, although more or less characteristic of 
Z anthoxylum , are by no means confined to this genus. A 
glance at the list at the end of the present paper will 
sufficiently demonstrate this fact. Nor are the trees bearing 
them limited in their geographical distribution ; for, while 
the Zanthoxylums occur in various parts of Africa, Asia, and 
America, the other genera are found all over the tropical and 
semi-tropical portions of the globe. 
In spite of the frequency with which these corky excres- 
cences are found in Museums, there does not appear to have 
been any attempt to describe their nature or development. 
My attention was first drawn to them by Mr. Walter 
Gardiner, who placed at my disposal material of Z anthoxylum 
alatum collected at Kew Gardens, and suggested that it 
might be of use to have the development of the cones care- 
fully traced in at any rate one species. In working out the 
development of the cones, I have had the advantage of 
abundant material, generously supplied by the authorities at 
Kew, both of Zanthoxylum alatum and of Caesalpinia Nuga. 
As there appears, however, to be no considerable difference 
in the development in the two cases, I have contented myself 
with a description of the former. 
In both of these plants the cones arise, in the first instance, 
as corky cushions beneath the thorns (Fig. 3) ; and there is 
no reason to doubt that this is their point of origin in other 
plants, of which old trunks alone are available for examination. 
In some of these cases, indeed, scars may be observed at the 
summits of the cones, while occasionally a minute thorn may 
be found still attached in this position. 
The thorns of Zanthoxylum alahim , in spite of their non- 
stipulate nature, appear in pairs at the bases of the leaves 
with such regularity that it is easy to trace them into the 
young bud (Fig. 4). A series of transverse sections through 
1 Guide to North Gallery, Kew, No. 381. 
