282 TRANSACTIONS OF THE CANADIAN INSTITITE. [VOL. V. 



investigated, grew. They were found as has been already stated, 

 virtually submerged in a peat-bog, and as a consequence, absence of 

 proper water supply which has been noticed as a predisposing cause of 

 apogamy, would not make itself felt. Possibly prothallia from the rich, 

 rather dry soil of the Don valley might yield a greater number of 

 examples. If we may infer apogamy from the presence of prothallial 

 tracheides, the gametophyte oi Botrychiunivirgiiiianiiin is unique among 

 the eusporangiate vascular Zoidogama, in this respect ; unless the phe- 

 nomenon is shown to be present in the tracheid-bearing Cycad endos- 

 perms described by Bower, and apogamy can no longer be considered 

 as peculiar to the leptosporangiate Filicinece. 



Returning to the young sporophyte, the shoot-organs and the root 

 possess fairly well marked apical cells, as is shown by Campbell^^ to be 

 true also of the mature spore-plant. Figure 52 represents the terminal 

 meristem of the young stem in vertical section. At a is probably the 

 apical cell. In figure 53 the same region is shown in horizontal section. 

 In figure 54 is the apex of the cotyledon in longitudinal section. Figure 

 55 represents a long section of the apex of the first root in an embryo 

 which has not yet broken through the calyptra. A large primary 

 segment is found on the side of the pileorhiza, a state of affairs rarely 

 seen in later stages of the root, as subsequently the small cells of the 

 inner part of the root cap abut immediately on the apical cell. This is 

 possibly to be explained by the comparatively slight development of the 

 pileorhiza which consequently requires only very occasional contributions 

 from the apical initial. The root of BotrychiuDi vwginiayiuni is an endo- 

 trophic inycorhiza and, as has been shown by Frank, there is a tendency 

 to degeneracy in the root-cap of roots of this type. The apical cell is 

 much more active on its flanks although even here it divides slowly, 

 compared with the apical initial of the leptosporangiate FilicinecB. In 

 figure 56 the root-apex is seen in transverse section, and unlike that of 

 the stem, its initial cell is triangular in this plane. 



Figure 57 shows an interesting case of polyembryony corresponding 

 to that described by Treub^7 in Lycopodium cernuujii. It was first 

 noticed after a series had been made of what appeared externally to be 

 a bifurcated embryo. The central cylinders of two plants, a and b, are 

 shown ; a is larger and much more abundantly supplied with reserve 

 food-materials, which cause it to stain more intensely ; h is smaller, less 

 developed, and in a condition of malnutrition as is indicated by a cor- 

 responding paleness of hue ; a^ is the second root of embryo a, and is 



26. Campbell. Mosses and Ferns ; pp. 232, 235. 



27. Etudes sur les Lycopodacties ; Extrait vi., p. 11. 



I 



