On the Anatomy and Histogeny of 
Strychnos. 
BY 
D. H. SCOTT, M.A., Ph.D., F.L.S., 
Assistant Professor in Botany , Normal School of Science and Royal School 
of Mines , 
AND 
GEORGE BREBNER. 
With Plates XVIII and XIX. 
T HE dominant position which the Dicotyledons unques- 
tionably hold among existing forms of vegetation is 
probably due in a greater degree to their method of secondary 
growth in stem and root, than to any other single character. 
The ability to increase indefinitely the amount of me- 
chanical, conducting and storing tissues in the axial organs, 
in proportion to the increasing development of the foliage, 
has more or less generally existed in all the most successful 
classes of plants ; but it is in the Dicotyledons that the 
highest differentiation of the secondary tissues is attained. 
The ascendancy of the Dicotyledons is most marked among 
those forms in which the duration of life renders a con- 
siderable secondary growth possible. The study of the modi- 
fications in the secondary formation of tissue in this class is 
therefore an important branch of biological inquiry. Though 
the process in its typical form is so well known, the recent 
work of Robert Hartig and others shows that there is still 
[Annals of Botany, Vol. III. No. XI. August 1889.] 
