208 DR. LINDSAY ON THE SPERMOGONES AND 
2. Frequent resemblance of spermogones or pycnides to various minute parasites with 
which they are associated, viz. :— l 
(a) Micro-lichens*, especially athalline species of :— 
Verrucaria (ez. V. gemmifera and pygmæa). | Pharcidia. 
Arthonia. no Phæospora. 
Endococcus. | Tichothecium. 
(b) Micro-fungi, especially species of Spheria, though sometimes also Torula. 
(Ez. Torula lichenicolat.) 
(c) Fungo-lichens, such as the so-called. species of the provisional genus Microthelia, 
3. Occasional association of spermogones or pyenides of lichens, in the same hand 
specimen, with those of Fungi, from which they are externally undistinguishable. 
Ez. The pyenides of Dichena rugosa, Fr. 
4. Resemblance (external) of spermogones to pyenides, and vice versá. 
In most of the foregoing cases the true nature of the conceptacle can only be deter- 
mined by careful microscopical examination, which shows at once the character of the 
contained corpuscles. In the case of most apothecia, even when young, before develop- 
ment of the sporidia, the hymenium ean be distinguished by its iodine reaction]. Where 
sporidia are present, the conceptacle, whatever its form, may be separated from the 
eategory of spermogones or pyenides, though there are occasional sources of difficulty in 
the exceptional cases in which spermatia or stylospores occur in the same perithecia with 
sporidia $, or in which stylospores resemble sporidia. The distinction between the sper- 
mogones and pyenides of fungi and those of lichens is not so easy unless when lichen- 
apothecia occur, and the secondary organs in question manifestly belong, or may legiti- 
mately be held to belong, to the species to which the apothecia are to be referred. Where, 
however, lichen-apothecia are absent, or fungus-perithecia are present, the difficulty of 
determination may be insuperable ||. 
5. Spermogones and pyenides are frequently extremely difficult of detection, or are 
apparently absent, by reason of their minute size Y, or their being concolorous with the 
thallus. 
Ex. Lecanora parella. 
* Vide the author's ** Enumeration of Micro-Lichens parasitic on other Lichens.” Quart. Journal of Microscopical 
Science, Jan., April, and October, 1869. 
+ Its spore-chains are apt to be confounded with stylospores, a circumstance that has led to error in my paper on 
* Arthonia melaspermella,” p. 271, pl. 6. f. 6, as pointed out in that on * New Lichenicolous Micro-Fungi," p. 533. 
Vide also the micro-fungus of Lecanora calva. 
t I have, however, elsewhere shown (as I think, conclusively) that the said reaction cannot be always relied upon 
as a lichenic test or character. (Vide papers on * New Lichenicolous Micro-Fungi,” p. 592, * Arthonia melasper- 
mella," p. 283, “ Otago Lichens and Fungi,” p. 423; and * Parasitic Micro-Lichens,’ p. 2.) 
§ Vide p. 200. || Vide pp. 196 € 199. 
€ Examples of extreme minuteness are to be found in Opegrapha herpetica, nos. 1, 2. 
