112 SUMMARY or CURRENT RESEARCHES RELATING TO 



(an editor of a journal in the cause of Microscopy objected to my 

 papers on the ground that I could not expect to gain credence), I only 

 trust microscopists will investigate ; if my theory is false, let it fall." 



Lichenes. 



Lichen-studies.* — In the course of a reply to Herr Forssell's 

 criticism on his " Lichen-studies," Herr H. Zukal repeats the main 

 points in which he dissents from Minks's interpretation of the 

 development of lichens. 



The structures described by Minks as " gonocysts " actually occur, 

 but are only gonidia which, by a peculiar process of growth, have 

 got extruded on to the superficial crust, where they acquire an appear- 

 ance so peculiar that they are with difiiculty recognized as metamor- 

 phosed gonidia. Zukal proposes for them the term Exogonidia. 

 These may, in certain circumstances, develope into a new lichen- 

 crust. In this whole process there is nothing very strange ; it may 

 be regarded as simply a modified formation of soredia. 



" Minks's gonangia " are spherical colonies of Palmella or Gloeo- 

 cystis, overgrown and inclosed by thick-walled brown lichen-hyphae. 

 His " microgonidia" are moniliform rows of spherical strongly re- 

 fractive and greenish particles of protoplasm, which fill up the hyphaa 

 of many lichens, and sometimes give them a peculiar appearance. 



Lichens of Scandinavia-f — In reviewing the genera of Scan- 

 dinavian lichens, Herr K. B, J. Forssell proposes a general classifica- 

 tion, the main feature of which is a division into five primary groups 

 dependent on the structure of the spores, viz. (1) unicellular, and not 

 muriform ; (2) bicellular, and not muriform ; (3) quadricellular, and 

 not muriform ; (4) multicellular, and not muriform ; and (5) multi- 

 cellular and muriform. The lichens with unicellular spores are again 

 classified as follows : — 



A. Spores coloured. 



(1) Discocarpi (Alectoria, BuelUa muriopsis). 



(2) Coniocarpi. 



a. Thallus fruticose (SpTiseropJiorus). 



h. Thallus crustaceous {Calicium, ChsenotJieca). 



B. Spores hyaline. 



(1) Asci with few (not 8) but large spores. 

 a. Thallus fruticose {Alectoria, &c.). 



h. Thallus crustaceous (Lecidia sanguinaria, Pertusaria). 



(2) Asci with 8-00 usually small spores. 



a. With chroococcus-gonidia (Omphalaria, Synalissa). 

 h. With palmella-gonidia. 



a. Pyrenocarpi (Thelocarpon, Trimmatoihele). 

 13. Discocarpi. 



* Spores very numerous (Acarospora, Biatorella). 

 ** Asci with at most 24-32 spores. 



t Apothecia lecanora-like (Lecanora, &c.). 

 tf Apothecia lecidea-like (Lecidea, &c.). 

 * Bot. Centralbl., xxiii. (1885) pp. 292-6. 

 t Bot. Notiser, 1885, pp. 33-57. See Bot. Centralbl., xxiii. (1885) p. 37. 



