163 
that M. betulinum was I-septate and M. bicolor not so: the 
answer lies in a peculiarity of the contents of the spores. In 
M. bicolor there is, in the majority of cases, a clear central oil- 
guttule, which ma owever, sometimes le towards either end, 
drop with a square outline towards the centre of the spore. In 
many, but by no means all of them, there is therefore, under a 
low power such as Link used, a distinct simulation of a median 
septum. This appearance vanishes altogether under a higher 
power, but has misled several observers, Greville, Vestergren, ete. 
As regards outward aspect, there seems to be a decided tendency 
in M. bicolor to burst out through a roundish opening, and in 
M. betulinum through an elongated lanceolate fissure. But on a 
wider examination of many specimens t this rule is seen to be 
ris ohh = so ee exceptions that it is ee | to name the 
two s s by external appearance only. fact they may not 
be really. ‘distinct, “bk as Tulasne thought ‘0% extreme forms of 
one species. Personally I incline more and more to this view 
of them as the end terms of a lengthy series, but in the biel 
of cases the spores appear as if perfectly distinct, and m 
thousands of species accepted at the “preset poe both in fungi 
and in other groups, rest upon no better foundatio 
The following exsiccata, among others, have bese examined : — 
No. 1. M. bicolor, Nees (spores 10-12 x 6-8 1). 
“*M. discolor,” Holl, Schm. et Kunz. no. (167! 
““M. betulinum,”’ Desm. Cr ypt. Fr. no. 
Moug. et Nestl. Stirp. pee no. 670! 
a Westd. Herb. Crypt. Belg. no. 182! 
Ellis, N. Amer. Fung. “a 960! 
MM. "bicolor, > Wl. et Ev., N. Amer. Fung. ser. ii. no. 2390! 
(the same as no. 960, and sent out as a correction 
of the mistake). 
No. 2. M. pear Schmidt § Kunze (spores 13-16 x 5-6 y). 
“©M. betulinum,’? Schm. et Kunz. exs. no. 208! 
‘“‘M. bicolor,’ Roum. Fung. Sel. ve Noor 
”» ; Fekl. Pung. Rhen. no. 84! 
” ; Syd. Mycoth. Germ. 143! 
Herb. Gerard, 2 Poughkaspete, se ve 
33 Herb. Berk. ‘“‘ Thorney, Cambs.’ 
"Herb. Curtis, “ eee ee ae 
s levatum,”’ Tab rd. no p-p- 
Dilyncsspiere e oe: Parts e100 
betulinu m, &S 4 
”? 
ae 
