OF FILAMENTOUS, FRUTICULOSE, AND FOLIACEOUS LICHENS. 119 
lens, and even with its aid, difficult of detection, as in many Parmelias, Physcias, 
Evernias, &c. In some cases it is so large and patent as at once to be recognised 
under the lens, as in Cladonia, some Parmelias, &c. 
Colour—is generally blackish or brownish; in some Physcias and Placodiums 
itis orange-red ; and in Usnea and Ramalina it is concolorous with the spermogone 
and thallus, and hence is extremely inconspicuous. In exceptional cases it is 
pruinose, as in Physcia pulverulenta, in which species, also, it is sometimes of a 
rose-red colour. 
VII. Chemical Characters.—No portion of the spermogonal tissues ever gives a 
blue reaction with iodine, as the thecze and other elements of the hymenial 
tissues of the apothecia do. But the spermatia are rendered sometimes more 
distinct by being coloured a deep reddish-brown. 
VIII. Function of the Spermogone.—lIt is generally supposed, by continental 
observers, that the spermogones are the analogues of male organs; but no im- 
pregnatory or fecundating influence on the spore has yet been distinctly observed 
or proved. In connexion with speculations as to their function, it is important 
to note :— 
. The universality of the occurrence of spermogones in lichens. 
. Their intimate relation, as regards position, to the apothecia. 
. Their priority in development over the apothecia. 
. The general resemblance of the spermatia to the spermatozoids of other 
cryptogams, though they are destitute of all appendages. 
5. The differences in form and structure between spermatia and spores. 
The former are solid, homogeneous, of extreme tenuity, elongated, 
colourless, of almost uniform shape and size. The latter are hollow, 
with heterogeneous contents, frequently septate, usually spherical or 
oval, shortish, frequently coloured, varying greatly in size and form. 
6. The absence of germinative power in spermatia. 
7. The relative size of the spermatia and spores,—the former being infi- 
nitely more minute. 
8. The relative number of spermatia and spores,—the former being infi- 
nitely more numerous. 
IX. Hfects on Classification, &c., of the discovery of Spermogones.—What 
are now ascertained to be spermogoniferous states of many lichens were regarded 
by the older lichenologists as separate varieties, species, and even genera; hence 
the discovery of spermogones has been the means, infer alia, of greatly reducing 
the number of lichens, and of simplifying their classification and nomenclature. 
eo bt = 
IJ. PycnipEs. 
The Pycnides of lichens may be described generally as externally resembling 
in form, colour, site, &c., the spermogones, from which they can be distinguished 
