1908] BARNES & LAND—CUPULE OF MARCHANTIA 409 
elevation continues the line of the posterior rim and so suggests the 
circular cup of Marchantia. 
The superficial origin of the gemmae is thus perfectly clear. 
They cannot be considered as in any sense homologous with the 
chlorophyllose filaments of an opened air chamber, nor has the cup 
any relation to the epidermal roof. The thicker part of it contains 
air chambers, and the thin part is simply a scalelike outgrowth of the 
epidermis. The difference between an air chamber and a cupule 
becomes especially striking when a cupule originates near an air 
chamber, as shown in figs. 2, 7, 10, 14, at J. Then, although the 
gemmiparous cells are seen to be superficial, they evidently represent 
cells that otherwise might produce not only the roof, filaments, and 
floor of an air chamber, but also a considerable portion of the thallus 
beneath the air chamber. In figs. 2, 7, 70, the line, #, #, can be 
followed clearly, showing how deeply the gemmiparous cells involve 
the tissues of the thallus. It is not surprising, therefore, that the 
gemma cup, though of superficial origin, is a depression in the thallus, 
and that air chambers clothe its sides. 
Incidentally we may add that the origin of the gemmiparous cells, 
as herein shown, precludes our acceptance of GOEBEL’S conception 
that in Marchantia the gemmae are homologous with “slime papil- 
lae.’s The formation of mucus cannot be considered as a special 
function of any particular cells, though the so-called slime papillae 
have the name of “ secreting” it. In fact young cells of very different 
origin and fate form mucus, and it is doubtful if any of the younger 
Ones fail to form it. These “papillae” are purely superficial organs, 
and Scarcely agree with the gemmiparous cells in anything except 
that at one time both project above the surface. How can the latter, 
Which involve so considerable a part of the thallus, corresponding, 
as above shown, to the whole air chamber region and two or more 
yers of cells below it, be properly likened to such transient and 
Superficial outgrowths as the “slime papillae”? ‘To pronounce the 
two homologous throws no real light upon the nature of the —— 
for the production of which there is such early and striking preparation. 
THE University or CHIcAco 
—* Gorse, K., “Die Brutknospe von Marchan 
ner Schleimpapille homolog betrachten werden.” 
| Flora 98:314. 1908 
tia und Lunularia kann auch als 
Archegoniatenstudien 
