204 DR. LINDSAY ON THE SPERMOGONES AND 
latter. Of this I have not had opportunities of satisfying myself: but there can be no 
doubt that spermogones frequently affect sites that render it impossible for them to have 
preceded the apothecia. They grow, for instance, on mature and old apothecia them- 
selves—on disk and exciple alike,—in which positions they could only have been deve- 
loped at a subsequent period to the organisms, which form their bases of support. More- 
over, the same sites are occasionally occupied by pycnides *, which are frequently (appa- 
rently) substitutional for spermogones, and which, whether occurring with or without 
associated spermogones or apothecia, seem to hold the same rank and position as sper- 
mogones in all material respects (e. y. site and period of development relative to the 
apothecia) Again, an argument has been drawn from the occasional resemblance in form 
and structure of séylospores to sporidia—sometimes of the same species T—in favour of 
the functions of both these groups of corpuscles being the same, regarding them as 
reproductive bodies, possessed of the power of germination. It would, however, be quite 
as legitimate to argue from their occasional resemblance, on the other hand, to spermatia, 
that stylospores are non-germinating, but impregnating corpuscles of the nature of sper- 
matozoids! In truth it is obviously utterly unsafe and improper, in the present state 
of our knowledge of the process of reproduction in lichens, to consider mere occasional 
resemblances—sometimes more supposed than real—as grounds for inferences regarding 
function. 
Spermogones and Pyenides as characters in Classification. 
Assistance may occasionally be derived, in the determination of species or genera, from 
the character of the spermogones or pyenides 1. 
Ex. Lecanora subfusca, nos, 3, 11. Ex. Lecidea fusca. 
sophodes, no. 1. —— quernea. 
Lecidea myriocarpa, no. 1. -— sublurida. 
parasema, no. 15. Opegrapha vulgata. 
disciformis, no. 1. Arthonia gregarla. 
—— Ehrhartiana. 
But in many at least of these cases the distinction may be sufficiently made from other 
characters, e. y. those of the sporidia. Nylander and other systematists sometimes use 
the spermogones or spermatia as distinctive characters. Thus Nylander points out that 
Platysma commixtum is scarcely separable from P. falunense, save by its spermatia, 
nor Physcia adglutinata from P. obscura. Bearing in mind the polymorphism of sper- 
mogones and their contents, it is obvious, however, that it is unsafe to place confidence 
in these organs as furnishing specific characters. It is right that the systematist, in 
defining his genera and species, should avail himself of all natural characters in an 
arrangement which itself claims to be natural. But the tendency of nomenclators and 
* They occur on apothecia in Lecanora ferruginea, no. 1. 
T Illustrations of such resemblances are to be found in Arthonia astroidea, no. 1; Verrucaria biformis, no. 3; 
the micro-fungus of Lecanora calva; and the genus Strigula. Vide also Proceedings of the Royal Society of Edin- 
burgh for 1859, p. 181; and author's paper on ** Polymorphism," p. 9. 
i Vide Summary of Characters of Spermogones and Pycnides in Edin. Royal Society * Proceedings,’ pp. 177, 178, 
