On THE PrrHOPHORACEA. ali 
knowledge of the nature of this difference. I think it not improbable, 
that an extremely thin layer upon the surface of the cell-membrane has 
been transformed from cellulose .to a jelly. — As a rule the helicoids 
occur only on terminal cells, but now and then such organs are formed 
also on iuclosed cells (pl. 5, fig. 1).— Regarding the function of the 
helicoid cells, the name at once indicates that it is principally to be 
an attaching organ of the plant. They are particularly well adapted to 
this purpose by the form which their upper part, the helicoid, has 
assumed. That they also have another purpose to serve, is very clearly 
hinted by the nature of their contents. The chlorophyll-coloured proto- 
plasm, which exists in such uncommon abundance, especially in the 
helicoid itself, no doubt officiates in the usual manner, and therefore the 
helicoid cells may reasonably also be regarded as active organs of 
assimilation. ’) That they have besides, like other cells of the plant, the 
power of absorbing liquid food for the plant, must be clear in itself. 
Il. ON THE REPRODUCTIVE ORGANS AND THEIR FORMATION. 
The reproduction of Pithophoracee is effected in two ways, viz. 1:0 
by the formation of spores, and 2:0 by the bringing forth of prolific 
cells. — Let us first describe the formation of spores. As I have had 
opportunity to observe it step for step only in P. kewensis nob., what I 
am going to say has its full bearing only on this species, but all signs 
seem to indicate, that the formation of spores in the other Pithophoracee 
is effected, in all essential particulars, in the same manner. Formation 
of spores takes place, as a rule, only in the cauloid part of the thallus; 
but each cell in this part has the power of bringing forth a spore. 
Thus, spores may be formed by the terminal cells as well as by the 
inclosed, by the cells of the principal filament as well as by those of 
the branches. It is, however, rather rare to find specimens, in which 
all the cells of the cauloid have really brought forth spores (such a 
specimen of P. Cleveana nob. is represented plate 2, fig. 12); generally 
the formation of spores has failed in one or more cells. Cells which 
have neither formed nor will ever form spores are not rare in the prin- 
cipal filament of the cauloid; in the branches, on the contrary, sterile 
') Thus the helicoids of Pithophoracee show a double analogy to the tendrils 
of certain phancrogamous plants, for instance with those of the Passiflorce. Both 
are parts of the stem, transformed into attaching organs, and both are besides at the 
same time active in some degree in the assimilation, 
