On a Cambial Development in Equisetum 
BY 
B. G. CORMACK, M.A., B.Sc., 
Assistant to the Professor of Botany in the University of Glasgow . 
With Plate VI. 
HIS paper includes an investigation of a cambial de- 
X velopment in modern Equisetaceae, an enquiry into 
the nature of certain features of Calamitae 1 , and a reconsider- 
ation in the light of the results thus obtained of the debated 
question of the unity of the Calamitae as a group, and of 
their systematic position. 
Regarding the problems connected with branching and 
infranodal canals, nothing will here be said ; and the question 
of the nature of the reproductive organs will be mentioned 
only incidentally. 
The main features of the Equisetaceae have been described 
in the works of Bischoff, Hofmeister, Thuret, Sanio, and 
Cramer, leading up to the monograph of Duval-Jouve and 
that of Milde. From the year in which Duval- Jouve’s work 
was published till now, there have been frequent additions in 
detail to our knowledge of this group, the chief contributions 
on points of vegetative structure coming from Rees, Pfitzer, 
Nageli and Leitgeb, Russow, Van Tieghem, Janczewski, 
1 The term Calamitae is here used, as by Solms-Laubach, to designate the stems 
and branches which, together with fructifications and other organs ascribed to 
them, constitute the group Calamarieae. 
[Annals of Botany, Vol. VII. No. XXV. March, 1893.] 
