51 
blue reaction with iodine has long since been proved falla- 
cious, inasmuch as, while it is absent in many true Lichens, 
it is present in many true Fungi. Professor Karsten 1 de- 
scribes a beautiful violet colour as developed in the stylo- 
spores of some Sphaeriee by a dilute solution of iodine, and 
he refers to this as the first known example of a starch-reaction 
in the stylo spores or spores of Fungi. A similar reaction occurs, 
however, in the filamentous excrescences of some species of 
Erysiphe (Tul.), in the tissues of the fruit of Septoria ulmi 
(Mold), and in the mycelium of Polystigma rubrum and P. 
fulvum (Bary). Currey 2 describes the same starch-reaction in 
the spores of Amylospora tremelloides. Nylander points out in 
various papers 3 how impossible it is to draw any sharp boun- 
dary-line between Lichens and Fungi. The hymenium in 
Fungi is generally yellow with iodine, just as it is (or some 
of its elements are) under the same reagent occasionally in 
true Lichens. In Hysterium elatinum, Fr., as in the Lichen- 
genus Graphis, the hymenial gelatine 4 is not coloured by 
iodine, but the spores become blue. In like manner, Hyste- 
rium Prostii, Dub. cannot be distinguished from the Lichen- 
genus Opegrapha. In some true Lichens (e. g. Parmelia arn- 
bigua ) the hymenial gelatine is either not coloured or obscurely 
coloured by iodine. Professor de Bary, a first-rate authority 
on the anatomy and physiology of Fungi, regards gonidia 
as the only means of distinguishing Lichens from Fungi 
(Ascomycetes) . 5 Inasmuch, therefore, as the parasite- 
genera Abrothallus, Celidium, Scutula, Phacopsis, and 
Sphinctrina , do not possess gonidia, he would arrange them 
with Fungi : as did Montagne , 6 a Cryptogamist who 
was equally at home among Lichens and Fungi. Such 
a distinction would enable Lichenologists to appropriate cer- 
tain plants hitherto considered Fungi, such as Agyrium 
1 “ On the Peculiarities of some Stylospores of Sp/uerice,” ‘ Botaniscbe 
Untersuehungen,’ 1S66 ; or translated by Dallas iu ‘ Annals of Nat. His- 
tory,’ vol. xix, 1867, p. 356. Vide also ‘Quarterly Journal of Science,’ 
July, 1867, p. 392. If, however, Karsten is correctly translated by Dallas, 
I am not led to place much confidence in his accuracy of observation or 
judiciousness of inference. 
2 ‘Quart. Journal of Science,’ July, 1867, p. 392. Vide also author’s 
paper on Arth. melaspermella, p. 284. 
3 “On Distinction between Lichens and Fungi,” ‘Flora,’ 1864, pp. 
421 and 558. “Ad Historiam reactionis lodi apud Lichenes et Fungos 
Notula,” ‘ Flora,’ 1865. 
* Vide author’s paper on Arth. melaspermella, p. 2 S3. 
5 “ On the Morphology and Physiology of Lichens and Fungi,” 
in Holfmeister’s ‘Handbuch der Physiologischen Botanik,’ 1S66, p. 
271. 
6 ‘Ann. des Sciences Nat.,’ vol. xvi, 3rd ser., p. 78. 
