284 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. V. 



marked pith, figure 61 m. The pith communicates with the external 

 fundamental tissue through a gap caused by the exit of the cotyledonary 

 trace, as has been described by Van Tieghem^^. The internal endodermis 

 discovered in the younger portion of the stem of Botrychium Lunaria 

 and others of the Ophioglossacecs by Van Tieghem^^ and Poirault^", is 

 not present in this species, although the external endodermis is well- 

 marked, only disappearing opposite the foliar gaps. The bast-tissue 

 originates first in the young central cylinder and seems never to have 

 any secondary additions from the activity of the cambium. Graf zu 

 Solms^i has thrown doubt on the existence of secondary wood in the 

 OphioglossacecE, but in this species there can be no uncertainty as to its 

 presence ; in fact, the wood is practically all secondary, as may be 

 learned from the radial arrangement of its matured elements and by 

 following the course of its development, figure 6}, x, and figure 64 x. 

 The first-formed wood-elements are reticulately sculptured and are never 

 of the ringed or spiral type. In this respect they resemble those of the 

 stem of the MarattiacecB, and, in fact, also those of the OsmundacecE ; for 

 the groups of typical protoxylem elements found in the upper region of 

 the bundles of the latter, really belong to the leaf-traces. It is more than 

 probable that the absence of typical primitive tracheary tissue in all 

 these cases, is due to the very slow growth of the stem, a phenomenon 

 which renders their presence unnecessary. The writer has noticed the 

 absence of these elements in the slowly growing stems of species of 

 so-called polystelic PrimulcE, viz : — P. Auricula dind P.farinosa. 



During this investigation, the rather interesting observation has been 

 made, that the periderm-tissue first described in the OphioglossacecB by 

 Russow3^ and Holle33, is formed in Botrychium virginianum at the bases 

 of defunct leaves, and thus is merely an abciss-layer. Figure 65, from a 

 photomicrograph, shows a young sporophyte still attached to its pro- 

 thallium ; r is the first root and ,i'the base of the cotyledon ; /- and l^ are 

 developing leaves. As may be seen from the figure, the course of the 

 cotyledonary bundle x, has been interrupted by the interca lation of a 

 layer of periderm. Figure 66 shows the tissues in question under a 

 sufficiently high magnification to make clear the details of periderm 

 formation. By the continued growth of the latter the distal part of the 



28. Remarques sur la structure de la tige des Ophiogloss^es. Journal de Botanique, iv., Ann^e ; p. 407 



2g. Op. Cit. 



30. Recherches sur les Cryptogames vasculaires. Annales de Sci. Nat. Bot. Tome xviii. ; p. 170. 



31. Fossil Botany, p. 223. 



32. Mfemdel'Acad. Imp. des Sciences de St. Petersbourg. vii.Serie. Tome xix., No. i, p. 117. 



33. Bot. Zeit. 1875. Ueber Bau u. Entwieklung der Ophioglosseen, p. 12. 



