LICHENS UNDER THE MICROSCOPE. 611 
black. In some species, as Vephroma arctica and Parmelia 
perforata, the apothecium attains a large size. In Cladonia 
it is borne on the summit of a hollow stalk, called a pode- 
tium; in Calieium on a slender solid stem. Fig. 146. 
In the Graphides, or "written" lichens, the 
apothecia are elongated and narrow, branched 
or stellate, and bear a rude resemblance to 
written characters. 
In many genera, such as Verrucaria, the 
apothecia are closed, and these are called 
angiocarpous. These apothecia are usually 
black, conical, with a small opening at the 
summit. Their covering is sometimes called Spore-c: S tlie 
the perithecium. But there is no fixed line Wi» spores- 
of demarcation between the gymnocarpous and the angio- 
arpous lichens. 
The paraphyses are sometimes long and thread-like, and 
Fig. 147. 
simple colored spore of Calicium uevcenetm. 
Spores. a, sim 
5, diblastish Ramalina calica 
ietrabla sti *  Buellia mean spool 
d, acic ul: * Biatora rubel 
i - *  Collema Aaccidum. 
^ muriform " " Buellia pe 
easily separated, sometimes short and closely agglutinated, 
and, as in Arthonia, are sometimes entirely wanting. In this 
genus the exciple is also wanting. The paraphyses pm 
Spore-cases are generally colored Hm sometimes red « 
brown, by a solution of iodine. 
The spore-cases, which lie among the paraphyses, are sacks 
usually of an oblong or club-shaped form, sometimes lanceo- 
