232 PROF. R. Je HARVEY GIBSON ON THE AXILLARY 
SAGITTARIA. 
The axillary scales in Sagittaria sagittifolia, described by 
Nolte so long ago as 1825 (8), are very numerous, as evidenced 
both by dissection and by transverse sections. Each scale begins 
as a multicellular ridge, 6-12 rows in thickness (Pl. 5. fig. 5). 
Each epidermal cell or cell-row gives rise by transverse division 
io a filament or plate which may remain distinct, or, as is more 
usual, grow in conjunction with other cell-rows or plates for a 
considerable distance, finally separating into numerous free 
filaments or plates. In consequence the closely packed young 
leaves are surrounded on all sides by succulent cellular threads 
or masses. 
Buromus. 
In Butomus umbellatus the bases of successive leaves are 
separated by numerous filamentous scales, some thread-like, 
others two or more cells broad, arranged and developing in a 
manner quite similar to those of Alisma Plantago. Indeed, 
fig. 12, Pl. 6, might stand for a longitudinal section of the base 
of an axillary scale of Butomus as well as for that of Alisma. 
HYDROCLEIS. 
The axillary scales in Hydrocleis nymphoides recall those of 
Sagittaria both in structure and mode of development. Each 
scale arises from a multicellular axillary ridge, and the cell-rows 
separate distally into numerous elongated plates or filaments. 
In consequence of the crowded arrangement of the scales the 
young leaves, as in Sagittaria, appear as though completely 
imbedded in a parenchymatous mass. The nuclei of the cells of 
the scales are long, rod-shaped, and deeply stainable. Dutailly (9) 
describes axillary scales in Hydrocleis Humboldtii, and remarks 
that they completely envelop the young leaves, acting as a 
protective sheath and arising soon after the leaves themselves. 
HALOPHILA. 
The genus Halophila has formed the subject of an exhaustive 
memoir (10) by Prof. Bayley Balfour, in which the morphology 
of “ squamulæ intervaginales,” as the axillary scales were called 
by Irmisch, is discussed. To this I shall have occasion to refer 
later. 
