1 14 Brebner . — On the Prothallus and Embryo of 
position could not be determined, although there is every 
reason to believe that it was not far off the median line 1 . 
Prof. Farmer 2 , and likewise Prof. Campbell, states that it is 
the anterior epibasal octants which give rise to the cotyledon. 
The embryos of Figs. 1 6 and 1 8 agree with their observations 
in this respect, as they were in both cases presumably de- 
veloped near the growing apex of the prothallus, at least for the 
time being, the cotyledon being anterior. With regard to 
the embryo of Fig. 1 6, it was impossible to say which was 
the original axis of growth, as the development of the pro- 
thallus had been exceedingly erratic. The embryo of Fig. 18 
was from the prothallus of Fig. i, in which its position is 
indicated by the black dot. With regard to Fig. 1 5 from the 
prothallus of Fig. 2, the direction of the growing margin is 
indicated by the arrow ; but as this section is not median, 
it is impossible to decide which epibasal octants are giving 
rise respectively to stem and to cotyledon. With a view to 
try and settle this point for Danaea simplicifolia , as embryos 
were not available, a young plant which had only expanded 
its first leaf, or cotyledon, was microtomed along an axis at 
right-angles to the growing edge, as there was some doubt 
about the attached prothallus being entire ; in fact, it was 
probably only a large lobe with an adventitious cushion. Be 
that as it may, this series showed without a doubt that the 
cotyledon must have been developed from the posterior epibasal 
octants, and the stem-apex from the anterior, unless there 
had been subsequent rotation. This seems to indicate that 
in Danaea , at least, the orientation of the embryo is not 
constant. Seeing that the embryo penetrates vertically 
through the prothallus, any definite orientation as regards 
its epibasal octants becomes unimportant, so long as they are 
turned towards the upper side. This consideration gives the 
clue to the inconstancy observed 3 . 
1 Careful re-examination of the sister-section, which is rather thick, has shown 
that it contains the apical cell (or cells ?) of the stem and cotyledon, and that in it 
the line II ... II divides the embryo more nearly into two equal halves. 
2 Loc. cit., p. 267. 
3 This question cannot be considered as really settled till a far greater number 
