The Origin and Development of the Apothecinm etc. 
381 
genous hypliae, the cells of whicli are irregulär, large and thin-walled, 
with granulär, much vacuolated cytoplasm and a single large nucleus. 
Baur finds that secondary apothecia may be formed when the primary 
apothecium through growth in thickness of the thallus comes to be at 
too deep a level and is thus forced to degenerate. The ascogenous hyphae 
grow upwards in the side walls of the apothecium and later form a new 
hypothecium above the old apothecium. A third apothecium may be 
formed in the same way. These ascogenous Strands may be as much 
as two millimeters in length. 
Fünfstück (42) in 1902 gave a short summary of sorne of the work 
that had been done on lic-hens up to that time. He suggested a third 
possibility to explain the further development of so few carpogones in 
Farmelia acetabulum. He thought it possible that only a few reach sexual 
maturity, and that as to the others degeneration has not progressed so 
far that they are capable of developing in a purely vegetative manner. 
Fünfstück noted further that the development of secondary apothecia 
is not at all uncommon. He found that a length of two millimeters for 
the ascogenous Strands is rather a minimum than a maximum, and that 
they commonly grow to be a centimeter in length. Baur had thought 
two millimeters the maximum length for these Strands. 
Again in 1904, Baur (5) described the development of the apothecium 
in several lichens. In this paper he gives a more complete account than 
he had given in 1901 of the processes in Parmelia acetabulum and Anaptychia 
ciliaris. In the former he again calls attention to the fact that very few 
carpogones develope into apothecia, and now, following Fünfstück’s 
Suggestion, he writes that since spermogonia are in abundance it must 
follow that either cross fertilization is necessary or eise that the carpo- 
gones develop apogamously; that only a few develop, is due to unknown 
causes. In Parmelia samtilis all the carpogones develop to some extent, 
but only a few complete their development, and produce apothecia. Baur 
says that the impression is given that the vigorous development of an 
apothecium has some inhibiting influence upon the development of near- 
by Anlagen. In the asexual P eitiger as there is, according to Fünf- 
stück (42) the same relation in number of apothecia and Anlagen. The 
observations up to this time give no certainty either for or against sexu- 
ality in Parmelia acetabulum and P. saxatilis. 
From Baur’s observations on Anaptychia ciliaris, there is no apparent 
increase in the number of ascogone cells by intercalary divisions. A 
number of the cells of an ascogone, but not all, give rise to ascogenous 
hyphae. In Gryrophora, the carpogones are in groups which differ from 
