602 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VoL. VI. 
the young sporophyte. If any dependence is to be placed on ontogenetic 
results, it would appear that the primitive type of cauline stelar 
arrangement in the-Equisetacez, is not one in which the bundles are 
surrounded by individual endodermal sheaths, but is, on the contrary, 
that designated by Van Tieghem as gamodesmic. The appropriateness 
of this term, as describing the conditions present in the young stelar 
system of this group, will be discussed subsequently. 
Van Tieghem® has recently re-examined the central cylinder of the 
Ophioglossacee, as a result of the discovery made by Poirault® of the 
occurrence of an internal endodermis in the young stelar system of several 
species of Botrychium and Ophioglossum. Heconfirms Poirault’s results 
and describes the distribution of the endodermis in the young central 
cylinder of Botrychium Lunaria. The stelar system is tubular, and above 
the point of origin of the first leaf-tracehasan internal,as wellasanexternal, 
endodermis. The inner one rapidly disappears in the older region of the 
young stem. A similar state of affairs occurs in Ophzoglossum vulga- 
tum, although in this case, the stelar tube becomes quickly broken into 
separate strands on account of the overlapping of the foliar gaps. The 
endodermis in this species also disappears in the older region of the 
stem.. Poirault®* has described a somewhat persistent zz¢erna/ endoder- 
mis in O. Bergianum, O. capense, and O. elliptecum. Quite recently an 
internal endodermal layer has been described by Farmer’ as occurring 
in the interesting genus Helminthostachys. His own observations, to- 
gether with those of Poirault, lead Van Tieghem to the conclusion that 
the cauline stelar system of the Ophioglossacee is, above the exit of the 
first leaf-trace, astelic in the sense already defined. It is apparent also, 
although Van Tieghem does not call attention to this fact, that the 
primitive condition of the fibro-vascular tissues in the stem of this group, 
is gamodesmic in his sense, and in this respect, corresponds with that 
described by the writer as existing in the young stem of the Equisetacez. 
The recent investigations of Van Tieghem and Poirault apparently 
make it impossible to regard the central cylinder of the Equisetaceee and 
Ophioglossaceze as in any sense, monostelic. guzsetum arvense, the 
genus Botrychium and the genus Helminthostachys, which were de- 
scribed by Van Tieghem in his essay on Polystely as belonging to the 
latter type, are shown by a more complete study of their anatomy and 
development to possess a gamodesmic central cylinder (in the sense of 
5. Journ. de Bot., 1890, p. 405. 
6. Ann. d. Sci. Nat. Bot., 7 sér., tom. 18., p. 169. 
6a, Op. Cit., p. 169. 
7. Ann, Bot., vol. 13., p. 434. 
