1900 | CURRENT LITERATURE 221 
pulverulenta. His investigations extend and support the results of Baur 
1898). It will be remembered that Baur found again the trichogynes 
discovered by Stahl in members of the Collemacez, observed the sperms 
fused with their tips, and saw stages indicating that the trichogyne withered 
from above downward after fertilization. 
Darbishire finds the archicarps each with its trichogyne in the youngest 
portions of the lichen thallus, and so very numerous that 700-1200 may be 
present on a small lobe. The lower part of the archicarp is an hypha of two 
or three loose coils, and is situated below the layer of algal cells about mid- 
way between the upper and lower surface of the thallus. The multicellular 
trichogyne extends as a filament between the algal elements to the exterior, 
where it projects above the upper surface. Sperms were observed attached 
to the tips of the trichogynes, but older stages show only one fused with each 
structure. When an archicarp of the group is fertilized it immediately devel- 
ops rapidly, and, although others may show signs of fertilization and appar- 
ently start to develop, they finally disappear, and only one apothecium is 
formed, 
After fertilization some of the large cells in the middle region of the 
coiled archicarp enlarge and finally fuse, so that there results a swollen 
multinucleate cell, the ascogonium, in each lobe of which lies a nucleus. A 
system of much branched hyphz arises from the ascogonium, becoming the 
ascogenic hyphz, from which the asci arise. The paraphyses develop from 
sterile hyphe around, but entirely distinct from the ascogenic ones; the two 
systems of hyphe being readily distinguishable. The further development 
of the apothecium follows closely the older accounts. 
This investigation supports at all essential points the studies of Baur, and 
extends the evidence of sexuality to another family of lichens. It suggests 
the probability of the presence of trichogynes and the sexual act in many 
more groups than most botanists have been willing to admit in the past. In 
passing we should also note that the recent suggestion of Lindau in respect 
to the function of trichogynes appears very dubious. He has presented (1899) 
a theory that the trichogynes are organs whose function is to bore through 
the layer of algal elements to the surface of the lichen, thereby weakening 
this layer and allowing the apothecium to develop more readily and to push 
up from below. Darbishire shows that such a function for the trichogynes 
of Physcia pulverulenta is quite impossible, and that this operation is per- 
formed by the developing paraphyses. 
We should bear in mind that whatever are the probabilities of sexuality 
among the lichens, we have not the knowledge that may be regarded as 
Proof positive. We do not know the fate of the nucleus from the sperm, 
whether or where the fusion of sexual nuclei takes place, and withal we have 
a complexity of conditions in the multicellular trichogyne that is certainly 
very puzzling — B. M. Davis 
