220 ‘ BOTANICAL GAZETTE [MARCH 
at this point, but by no means separating the upper and lower portions. 
Walls now appear in the lower portion so that it becomes filled with solid 
tissue at the apex of which bodies which may be rudimentary. archegonia are 
sometimes found. In the upper portion the nuclei remain free in the proto- 
plasmic lining of the sac, 
At this stage, one or more pollen tubes enter, each bringing in two genera- 
tive nuclei, Each generative nucleus fuses with one of the free nuclei in the 
sac, and the several copulation products become surrounded by denser proto- 
plasm and soon acquire a membrane. They are now called zygotes, The 
zygotes germinate into long tubes, which grow down toward the base of the 
sac and penetrate the solid tissue there. Previous to this time this prothallial 
tissue has been increasing enormously and in the mature seed the fertile por- 
tion of the sac appears as a mere speck at the apex of it. At this stage the 
seed falls from the plant, 
The development of the embryo from the tube which arises from the 
zygote has already been described by Bower. 
The author suggests the following homology with the structures of the 
angiosperm sac. 
Angiosperms Morphological nature Gnetum gnemon, 
Egg apparatus = Archegonia = Fertile nuclei. 
Micropylar polar nucleus = Prothallium = Sterile nuclei of sik part 
of sac. 
Chalazal polar nucleus = Prothallium = Prothallium in lower part of 
sac. 
Antipodals — Rudimentary if s 
’ archegonia = Rudimentary archegonia on 
lower part of sac. 
Endosperm = Prothallium = Growing prothallium of low- 
er part of 
The conclusion is reached that the Gnetacez are very ancient in origin 
‘and that they must have originated before or at the same time with gymno- 
sperms (by this probably meaning the Conifere.) 
He is inclined to regard “the Gnetacee as the equivalent of the gymno- 
sperms and angiosperms combined and running parallel to these, having 
originated entirely independently of them. In these two parallel rows the 
Symnosperms may be compared to the Ephedroidez and the angiosperms to — 
the Gnetoidez.’ 
There will be objections to this interpretation if current views as to the 
geological history of the group are well founded._-CHARLES J. CHAMBERLAIN. 
Dara bearing on the problem of the sexuality of the lichens are gradually 
accumulating, and the most recent contribution is by Darbishire™ on ? hyscra 
™ DARBISHIRE: Ueber die Apothecienent wickelung der Flechte Physcia pal- 
verulenta (Schreb.) Nyl. Jahrb. f, wiss. bot. 34: 329. 1899. 
