372 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



though such specimens are far less liable than others. A 

 spirituous solution is not well calculated for Fungi, as it is apt 

 to change their colours. Dr. L^veille informed me that he 

 kept his Fungi clear of insects by always having a paper of 

 fresh Polypori, siich as P. versicolor, &c., amongst them, as 

 they are greatly jDreferred to any other, I have, however, 

 never tried this plan myself. 



b. LiCHENALES, Be7^k 



Aerial mycetals deriving nourishment, for the most part, 

 from the surrounding medium, and not from the matrix, con- 

 stantly producing in the thallus green bodies, resembling chlo- 

 rophyl (gonidia), either singly, in Uttle bundles, or in monili- 

 form rows; fruit contained in asci, or, as regards secondary 

 fructification, seated on sporophores. 



409. The principal points which distinguish Lichens from 

 Fungi are their mode of growth, their living at the expense 

 of the surrounding medium, their mostly perennial endurance 

 and slow growth, and the production of gonidia. If the true 

 Lichens be considered by themselves, their peculiar texture, 

 tartareous and crustlike in a vast quantity of species, and 

 in almost an equal number rigid and often brittle when dry, 

 but flaccid and flexible when moist, is characteristic without 

 having recourse to the fructification. If the Collemals be added, 

 we have gelatinous fronds approaching very near, in point 

 of texture, to many Algne. The fruit is formed after the 

 Ascomycetous type, and appears either under the guise of a 

 distinct perithecium, as in Splueria, an exposed disc, as in 

 Tymipanis, or a linear and frequently branched receptacle, as 

 in Rysterium or Glonium. So far there is little or no difler- 

 ence between the fruit of Ascomycetes and Lichens. It ap- 

 pears, too, from the labours of Itzigsohn, Tulasne, and others, 

 that in many cases there is distinct dualism, one form of fruit 

 following the ascomycetous type, the other the sporophorous. 

 Whether any autonomous genera exist with naked spores is 

 extremely doubtful. Both forms, however, exist in general 

 together on the same plant. In every case, except Ahrotha - 

 lus, and one or two allied parasitic Lichens, Tulasne considers 



