DopGE: RELATIONSHIPS OF FLORIDEAE AND ASCOMYCETES 169 
the young ascus (31) has seemed to indicate its resemblance to 
teleutospores and basidia rather than to any structures in the red 
algae. Dangeard first described the formation of the ascus in 
Pustularia vesiculosa as involving the fusion of two separate 
hyphae at their tips, a condition that was found later to actually 
be the method of origin of the binucleated basal cell in the 
aecidium cup of the rusts. Although Dangeard immediately 
corrected his error one can not doubt that it has been largely 
responsible for his whole theory of the sexuality and origin of the 
Ascomycetes. His views in this connection have received much 
attention and need not be considered further here, but the morpho- 
logical features of the process by which an ascus is formed from 
the penultimate cell of a ‘‘hook”’ or ‘“‘crosier” are so characteristic 
and of such widespread occurrence among the Ascomycetes as to 
Warrant more careful examination than has been given to them. 
This sort of structure occurs in’ genera as widely separated as 
Collema, Usnea, Lachnea, Morchella, Tuber, Aspergillus, and 
Pyronema. In all some thirty-five species have been figured as 
showing the ascus formed in this manner, and nearly all conform 
to the same type. Harper (53), who first figured conjugate 
nuclear division in the hook, and others have given a great deal 
of attention to this phenomenon and have fully discussed the neces- 
sity for some such arrangement as a means of providing that the 
nuclei which fuse in the ascus shall not be sister nuclei. The 
manner in which the crosier may become modified seems to be 
almost without limit, but the fundamental principle is maintained 
with a very few exceptions. Faull (40) claims to have examined 
Over thirty species and finds that the ascus arises from the penul- 
timate cell invariably in eleven of them. In other forms he de- 
Scribes the omission of the wall which ordinarily cuts off the end 
cell so that in such cases the terminal cell gives rise to the ascus, 
although the hook is well represented with its tip curved down. 
Modifications of the hook by proliferation, the growing out of the 
€nd cell to form a second hook, or the fusion of the terminal cell 
With the antipenultimate cell are variations which have also been 
described. W.H. Brown (19, 20), McCubbin (61), Claussen (26), 
Fraser (43), and others have described further ways in which the 
Crosier may be modified. 
