INVERTEBKATA, CRYPTOGAMIA, MICROSCOPY, ETC. 315 



assigns the priority to Korber's name. He points out that we have 

 here a division of ascophorous thallophytes, which has been claimed 

 by both liclienologists and mycologists, and does not himself decide 

 the question whether they are lichens or not, though they doubtless 

 belong to the Ascomycetes. He gives the diagnoses of five species 

 hitherto ascribed to Microthelia, and eighteen hitherto ascribed to 

 Didymosphceria. 



Lioheues. 



Colours of Lichens.* — Nylander thus sums up the facts regarding 

 the colour of lichens. That of the thallus is most commonly white 

 or nearly so ; less often dusky green, ruddy, yellow, straw-coloured, 

 orange, cinnabar, or black. It is not uncommon for it to be black or 

 blackish above ; and this colour sometimes extends to the rhizines 

 and hypothallus. 'J^he colour of the internal tissue is usually white, 

 but in some cases golden yellow or less often ochre ; in a few 

 instances scarlet or purple. The colouring matters are erythrinic, 

 lecanoric, and chysophanic acids, to which Nylander adds two more, 

 glaucinic and lecithophanic. 



The apothecia are sometimes colomdess, at other times black, 

 dusky, yellow, rose, flesh-coloured, ferruginous, or red ; but the 

 conceptaole and epithecium are seldom of the same colour. The 

 hypothecium is colourless or coloured ; the paraphyses colourless, 

 except at the tips. The spores are usually colourless, sometimes 

 dusky or blackish. 



The sperm ogonia are sometimes coloured on the outside, but always 

 colourless within ; the spermatia always colourless. 



Hypothallus of Lichens. t — According to Nylander, the prothallus 

 of lichens often passes insensibly into the hypothallus. By the pro- 

 thallus (not to be confounded with the prothallium of vascular 

 cryptogams which bears the sexual organs), he understands the early 

 stage of the hypothallus which proceeds at once from the germinating 

 spore. Both consist entirely of hyphas, scarcely exceeding 3-4 /x in 

 diameter. The hypothallus is usually more or less white, sometimes 



The veteran lichenologist takes the opportunity of again recording 

 his dissent from the fungo-algal lichen-theory of Schwendener ; 

 stating that the hypha) of which the prothallus is composed never 

 have the power of investing substances which are embedded in them. 

 No Protococcus or other alga can possibly enter into the composition 

 of a lichen, the gonidia being developments from the hyphal structure 

 itself. 



Algae. 



Structure and Classification of Scytonemaceae.t — In the most 

 recent of his important series of pai)er8 on the morphology and 

 biology of the rhycochromacero. Signer Borzi thus sums up his 

 results, as far as regards the Scytonemaceao : — 



1. The vegetative increase of the filaments takes place by repeated 



♦ ' Flora." Ixii. (I87UJ ]>. 557. t H'id.. p. .')74. 



: • Nuov. Giorn. Bot. Ital..' xi. (1879) p. 384. 



