402 BOTANICAL GAZETTE [DECEMBER 
whether it could possibly be homologous with an air chamber. 
From an a-priori consideration of the general character of the cupule 
and the air chamber this idea commended itself to us both. The 
walls of the cup, especially the thin, lobed margin, seemed to corre- 
spond very well with the epidermal roof of the air chamber, opened 
wide instead of having only a narrow orifice. The gemmae, borne 
upon a single cell arising from the floor of the cup, might well be 
Oe 1—Early stage of cupule; p, p’, ° Fic. 2.—Early stage of cupule; ?, Y’, 
undivided cells, primordia of two (?) as in fig. 1; w, probably a rim cell 
Semmiparous areas; a, apical cell; air between two gemmiparous areas; 
er Paes. apical cell; #, ¢, line showing tissues of 
thallus involved in a cupule. 
only a modified form of the chlorophyllose filaments of the air cham- 
ber. So natural and neat did the homology appear, that the brief 
prior statement of it by CAMPBELL (I. c.) was discovered with a dis- 
tinct sense of disappointment when we began to look into the litera- 
ture. But evidence for this homology could not be found there , 
and against it was to be put the fewness of the cupules, their jimita- 
tion to the median line, where the air chambers are least developed, 
and the fact that the gemmiparous region covers many times ; fr 
area of an air chamber. The matter evidently needed examination. 
Actual observation of the origin of the cupule speedily dissipated all 
