VOL. Xul. No. 7.—BOTANICAL GAZETTE.—JULY, 1888, 
Spore-dissemination of Equisetum.+ 
F. C. NEWCOMBE. 
( WITH PLATE IX.) 
The subject of spore-dissemination of Equisetum may 
be considered under three heads: 
I. Elongation of the axis of the spike 
ll. Structure of the sporangium-wall and its mode of 
dehiscence 
II. Structure and action of the elaters. : 
Unless otherwise stated, these notes are wholly on Equi- 
Setum arvense preserved in alcohol. 
J. Elongation of the axis of the spike.—In the immature 
spike the peltate scales which bear the sporangia on their 
inner surfaces are closely united edge to edge, forming an 
unbroken wall; but as the spores are nearing maturity the 
axis of the spike and the stalks of the peltate scales rapidly 
elongate, causing each scale to become separated by a con- 
siderable space from its neighbors. By careful comparison 
of cellular structure, this elongation seemed to be due to 1n- 
frease in length of cells. Longitudinal sections from the 
axis and scale-stalks of several spikes in which the scales 
Were about to separate were made, and similar sections from 
th 
h 
Sporangium, the first step in spore-dissemination 18 
accomplished. 
Pag Structure of the sporangium-wall and its mode of 13 
“Scence.—Each of the numerous scales of the spike is at- 
