441 
Reinke contents himself with de Bary’s definition of the lichen- 
thallus ; de Bary designates it as the vegetative organ bearing the 
apothecia, spermagonia, and in certain instances also pycnidia. 
This rather negative definition is accepted by most modern lichen- 
ologists who define the vegetative organ as the structure whose 
Prime function is to take up and assimilate food-substances. 
Reinke also accepts, or at least expresses his disinclination to. 
change, de Bary’s definition of the reproductive organs; that is, 
the reproductive organs are the apothecia and spermagonia. If 
the experiments and observations of Stahl* and Sturgis} prove 
correct it would be more correct to speak of the carpogone and 
Spermagone as the reproductive organs ; but since it is highly pro- 
bable that the spermagonia are merely parasitic fungi, or since 
their true nature is as yet problematical, we have no scientific au- 
thority to designate them as reproductive organs. This difference 
of opinion does not have any important bearing upon the question 
under consideration. It is, however, evident that Reinke con- 
Siders the spermagonia as reproductive organs. 
Reinke recognizes two portions of the Cladonia-thallus: the 
horizontal portion which is also called primary thallus or proto- 
thallus, and the vertical portion, or the podetium of lichenolo- 
gists. The term thallus is quite generally applied to the horizontal 
or primary thallus, while the term podetium is retained to desig- 
nate the vertical thallus. In all instances the podetium takes its 
Origin from the gonidial (algal) zone of the horizontal thallus. 
Whether the beginnings of the podetium are due to a sexual act 
°F not, is not definitely known. Krabbe and Reinke are inclined 
to believe that it is nonsexual. Reinke, however, hints at a fos- 
sible sexual act represented by a fusion of the nuclei of two neigh- 
boring hyphal cells. 
The primary axis of the podetium is negatively geotropic, 
thus differing essentially from the transversely geotropic dorsi- 
ventral horizontal structure of the primary thallus. If the po- 
detia branch, it is found that the negative geotropism decreases with 
* Stahl, E. Beitrage zur Entwickelungsgeschichte der Flechten, I. and I1., Leip- 
zig, 1877, 
t+ Sturgis, W. C. On the Carpologic Structure and Development of the Collem- 
aceae and Allied Groups. Proceedings of the American Acad. 25: 1890. 
