ON THE LICHEN-GONIDIA QUESTION. 
277 
. 2. a and b. Isidose globules of Collema furvum in different conditions, 
whence it is seen that the gonidia originate from the very begin- 
ning in the isidia themselves. 
3. Gonidia of Physcia parietina. 
4. Protococcus viridis, both equally magnified, and both from the same 
piece of bark, showing that, though sufficiently similar, they are 
yet not identical* 
5. Copied from Bornet (Pl.'x.), and showing the spores of Physcia 
parietina sown together with Protococcus viridis , sending forth 
filament-germs which insert themselves into or fix themselves 
upon the globules of the Protococcus. 
, ’6. Copied from Reess, and showing the filament-germs of the spores of 
a Collema entering into Nostoc lichenoides, Yauch. 
