284 DR. LAUDER LIXDSAY ON A.RTHONIA MELASPERMELLA. 



in the latter species also, the spores are pale blue. In the genus 

 GrapJiis the hymenial gelatine is w;^affected, or yellowish ; though 



a bluish coloration is sometimes yisible on the spores. 



While, on the one hand, the reaction supposed to be charac* 

 teristic of Lichens is absent in certain indubitable Lichens, it is 

 also present in certain indubitable Fungi. For instance, the tips 

 of the th€C(S in SpJiceria pedunculata^ Dicks., and S, Desmazieriij 

 Berk., and various other SpTiceri^e^ as well as in Feziza vesicularis ; 

 and the gelatine of the receptacles in Septoria ulmij Grev., strike 

 a more or less intense and beautiful blue with iodine *. 



In a recent note in the 'Flora' [Oct. 10, 18G5], Nylander 

 points out that the hymenial gelatine becomes bhce under iodine 

 in several species of JPeziza [e. g. jP. cocMeata, Huds., and P. vio- 

 lacea^ Pers.], the apices of the thecse, as in Lichens, being the 

 seat of the greatest depth of tint. In many other species [in- 

 cluding P, porina Pers., P, plumhea Fr., P.juncigena Nyl., P.nti- 

 della Fr., P. cerea Sow., P. repanda Wahl.] the thecse, or their 

 apices only, as is also the ease in many Lichens, assumed the blue 

 tint in question. He points out, further, that the same fungus 

 may give a different reaction with iodine according as it is freshly 

 gathered, or an old herbarium specimen. He found that the hy- 

 menial gelatine o£ Peziza Polytrichii, Schum., collected in Helsing- 

 fors, Finland, gave an intense blue reaction with iodine when fresh ; 

 whereas the same specimen^ when two years old, in an herbarium, 

 exhibited no coloration at all. Nylander and Leighton appear to 

 regard this different residt of age as pro tanto a distinguishing 

 feature between Lichens and Fungi, the same reaction occurring, 

 says Leighton [" Notulae Lichenologicse," no. 1, " On the Eeaction 

 of Iodine in Lichens and Fungi," Ann. Nat. Hist., Jan. 186(5, 

 p. 58], in Lichens whether they are old or recently gathered. I 

 can only say that such a statement is entirely opposed to ray own 

 experience, which led me to regard this criterion as equally fal- 

 lacious with the others that have from time to time been esta- 

 blished for the differential diagnosis of Lichens and Fungi t- 



Tulasne, Ann. des Sc. Nat. ser. 4. t. vi. p. 318 ; Nyl. Syn. p. 4. . 



t [The most remarkable case of coloration by iodine in Fungi is that of 

 Amylocarpns encephaloides^ Curr., described in the Proceedings of tlie Boyftl . 



Society for January 28, 1858. From a reexamination of this plant I can quite 

 confirm Dr. Lindsay's opinion that the criterion of age is fallacious. Amylo- 

 carpus oiceplialoides has been in my herbarium for nine years \ and although 

 the sporidia are not affected by iodine as they were at first, the viscid matter 

 surrounding them assumes the same intense purple colour which it did when 

 the plant was fresh. — Sec. L. S.] 





