209 DR. LINDSAY ON THE SPERMOGONES AND 
difficult subject of the process of Lichen-reproduction. I am far from being prepared 
to accept their interpretations, preferring to hold the alleged functions of spermatia and 
stylospores in lichens simply as not yet established. Meanwhile I venture to direct 
attention to certain of the anatomical or morphological relations of spermogones and 
pyenides, which can scarcely fail, I think, to bear materially on speculation regarding 
their supposed diverse functions. 
The present memoir contains, I think, ample evidence of the impossibility of drawing 
any scientific line of demarcation between spermogones and pycnides in lichens. In ex- 
ternal characters—form, colour, size, site,—they are frequently so much alike that it is 
impossible to distinguish the one from the other unless by microscopical examination, 
if indeed, in some cases, it is even then possible to decide to which category a given 
organ belongs! The sterigmata of the one, and the basidia of the other, are frequently 
simple, linear, or filiform supports, which give off spermatia or stylospores as terminal 
cellules or articulations. These corpuscles themselves are frequently of such a cha- 
racter that it is impossible to determine whether they should be regarded as spermatia or 
stylospores! Such, indeed, is the resemblance between spermogones and pycnides, sper- 
matia and stylospores, that while one group of lichenologists regards a particular con- 
ceptacle as a spermogone, and its contained corpuscles as spermatia, another, of equal 
attainments in microscopical skill and knowledge of lichens, describes them respectively 
as pycnides and stylospores*; or the conceptacle may be regarded as a spermogone, 
while its corpuscles have a stylosporie character! Hence also it happens that the same 
observer, with enlarged experience and more liberal views, regards at one time as a 
spermogone what afterwards he describes as a pycnide ! 
The following are some of the main points of resemblance and difference between sper- 
mogones and pycnides :— 
I. Resemblance. 
1. Gradation of spermatia into stylospores, or vice versá. 
Ex. Lecanora varia, no. 6. Ex. Opegrapha atra, no. 2. 
Lecidea Ehrhartiana, no. 1. Opegrapha varia, no. 7. 
Griffithii, no. 7. Arthonia gregaria, no. 2. 
—— abietina. Verrucaria epidermidis, no. 1. 
Graphis scripta, no. 2. 
2. Occasional ramosity of basidia. 
Ex. Lecanora ferruginea. Lecidea abietina, no. 9. Opegrapha varia, no. 7. 
3. Occasional occupation of the pycnidal cavity by elongated ramose filaments, as 
in spermogones. 
Ex. Lecidea Griffithii, no. 7. 
4. Occasionally the basidia give off two stylospores, just as sterigmata sometimes 
(apparently +) develope two spermatia. 
5. Occasional granularity of spermatia. 
* Vide my paper on * Polymorphism,” p. 3. 
+ Vide what I have already said of Errors of Observation or Interpretation, pp. 195, 197, 198. 
