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



is not followed by the formation of a cell-wall, such as has' been 

 described by Farmer and Campbell in Angiopteris, Marattia, and 

 Osniunda. From the study of many hundred archegonia in this stage 

 of development, the statement is made with some confidence that such 

 a wall is never present in Botiychium virginianuvi . In figure 37, is 

 represented an ajxhegonmin in which the ventral canal-cell has made its 

 appearance. One very rarely finds this canal-cell intact, as it quickly 

 disintegrates and in preserved material, at any rate, is represented by 

 an indistinct mass thrust against the wide base of the cervical canal- 

 cell. In figure 38, is seen a ripe ardiegoniuni which has ejected its 

 canal-cells. The apical cells of the neck are, as is usual in the Pteri- 

 dophj^ta, thrust outwards. At the same time one frequently notices 

 chromatolysis in the nuclei of the upper cells of the archegonial neck, 

 figure ^J, although this phenomenon is by no means invariably present. 



The mature o.^^ is large and possesses a very dense protoplasm, 

 which however, generally encloses a hydroplastid. The free surface of 

 the oosphere rises into a median elevation, the receptive prominence. 

 Figure 38, was drawn from a preparation in which a single spermatozoid 

 had entered the canal of the aixhegoniuni. It has not been possible to 

 follow the stages of union of the sexual nuclei. After fertilization, the 

 canal is generally occluded by the closing together of the neck cells, 

 figure 39, although this is by no means invariably the case, figure 40. 

 The oospore grows to many times its original size before the first 

 division takes place. Figures 39 and 40, represent two stages of the yet 

 undivided oospore. In figure 41, the first segmentation has occurred, 

 and the basal wall is horizontal, as in the other eusporangiate Pteri- 

 dophyta. In figure 42, the embryo has become divided into quadrants 

 by the median wall, which is the next to appear, and which, in the 

 majority of cases at least, is parallel to the long axis of the prothallium. 

 The transverse wall next makes its appearance at right angles to the 

 other two. In figure 43, is represented an embryo which has already 

 undergone further divisions. The upper octants have been sub-divided 

 before any similar activity has appeared in the lower segments. There 

 is no indication of a suspensor, and as the lower part of the embryo is 

 not loaded with food materials, it seems probable that the earlier 

 divisions in the upper octants, are for the purpose of thrusting the 

 young sporophyte deep into the prothallium, that it may be more easily 

 nourished and attain its characteristically large size without exposure to 

 injury. The divisions are not always so regular, as in the case of the 

 embryo represented in figure 43. In some instances, the basal wall is 

 rather oblique, and corresponding differences exist in the orientation of 



