: AS A SPECIFIC CHARACTER IN LICIIEKS, 49 



13 a curioua thing/' says he, ^Hhat neither the soredia of Mbn^ 

 tagnei uov pTiycopsis show colour-reaction." Subsequently, how* 

 ever, in the same paper, he admits that the thallus of R. foci- 

 formis occasionally shows the erythrinic reaction. The fact, as 

 stated by Nylander and Leighton, that no reaction occurs in JR. 

 fticiformis^ except in the soredia, while it occurs in B. Montagnei^ 

 save on the soredia, both species being, nevertheless, referable 

 botanically to the same type, is a specimen of the very unequal re- 

 suits of the application of the so-called " Test." There is no reaction 



+ 



in -B. Tiypomecha^ Nyl- ; and yet it is a tinctorial species, having 

 the common properties of the genus. With strange inconsistency, 

 as it seems to me, Nylander sums up : — " Thus are we now able, 

 with the aid of the hypochlorite of lime, with great facility to 

 separate and distinguish the species of this difficult genus, in 

 which heretofore the determinations have been often uncertain. 

 This reaction manifests also this remarkable fact, that determina- 

 tions ^^r/J?e?^Zy exact may be made even on specimens which are in 

 ^ young and sterile state, and in other respects very incomplete" 

 (p. 360) ! Leighton speaks of the erythrinic reaction being at 

 once visible in the Boccellcey some of which, nevertheless, he pro- 

 ceeds to say, show "no reaction," Indeed the papers of both 

 Nylander and Leighton abound in ambiguities or contradictions 

 of this description, 



.Genus Lecanora, — In L, tartarea there was generally more or 

 less of a blood-red colour * developed equally on the apothecial 

 warts and on the thallus, especially if mealy or aorediiferous 

 exhibited, however, usually only on friction. Sometimes the 

 colour was very faint, even in the white medullary tissue. As a 

 general rule the colour-reaction was faintest in corticolous forms. 

 In some cases \e.g, in a Loch-Lomond specimen, 1855] I found 

 no reaction. Nylander classes tartarea with pallescens, and sepa- 

 rates L. parella from both, ^' since its thallus does not exliibit any 

 reaction with the hypochlorite of lime." In the majority of cases it 

 does not; but I have met with the reaetion, exceptionally, more 



^ 



vividly developed than is common even in tartarea, For instance^ 

 in ordinary corticolous forms of i.^«r^7Zfl! [from Yorkshire, 1855] 

 I obtained blood-red, by friction of the exciple of the apothecia, 

 as deep and distinct as in tartarea] while in saxicolous forms, 

 from the Kyles of Bute (1852), the colour-reaction was even more 



This blood-red is exhibited by many crustaceous thalli, e.g. oi Lecanora, 

 UrceoJaria^ and Pertusaria. 



MNy. PROC. — BOTAXY, VOTi, XF. 



£ 



