308 BOTANICAL GAZETTE [cay 
out accessory cells in the form of nutritive cells, elaters, or 
columella cells. In all cases the hypobasal hemisphere is prox- 
imal, while the epibasal is distal. The archegone may be erect, 
horizontal or inverted, but the orientation is always normal and 
primitive; that is to say, the epibasal hemisphere, originating 
as the distal half of the egg, retains constantly the distal posi- 
tion. This distal-proximal arrangement of the first egg seg- 
ments is not disturbed in any important sense by the retarda- 
tion of the basal plane in such an embryo as that of Antho- 
ceros. Without further discussion at this point, it may be well 
to pass at once to the consideration of pteridophytic embry- 
ogenies, in order that their new developments may be brought 
before the attention. 
PTERIDOPHYTIC ORIENTATION AND SEGMENTATION TYPES 
Among certain genera of pteridophytes it is probable that 
the primitive bryophytic orientation of the egg is retained. 
Among others it is profoundly altered, so that the inverted 
embryogeny of the Lycopodine and of the leptosporangiate 
ferns presents itself for consideration. It will be shown later 
that the inverted embryo of the club-mosses and ihe 
inverted embryos of Polypodium and Alsophila are not directly 
comparable, the inversion having originated under probably dif- 
ferent stimuli in the ancestral types; that is, in a word, these 
is not one type of inverted orientation to be set over against 
the one primitive type of normal orientation. On the ae 
trary, inversion, semi-inversion, or rotation of the egg ™@y 
shown to have arisen in different phyla under different con 
ditions. 
Embryogeny of Equisetum.—This plant wa t early 
studied by Hofmeister, who gives some correct figures : f i 
Stages in f/. 77 of the work cited. His fig. 76 is pan 
excellent. The very early two-celled stage of the a a 
shown, but the horizontal first division plane is duly sales ; 
3 Ueber die Keimung der Equisetaceen. Abh. K. S. Gesellsch. d. WIS 4° c 
s among thore 
