Igto] BROW N—ASCOCARP OF LEOTIA 457 
the Ascomycetes is probably vegetative, and its replacement by 
the fusion of cells of separate hyphae or sister cells would give 
rise to a process quite similar to that in the rusts. While the above 
facts suggest a similarity between the Ascomycetes and the rusts, 
they do not appear to be sufficient to warrant the conclusion that 
the fusions and conjugate divisions in the two groups are phylo- 
_gicaapaaed related. 
Summary 
The ascogenous hyphae of Leotia have their origin at ie base 
of the ascocarp, probably from a one-celled ascogonium. 
The asci are formed at the tips of the ascogenous hyphae in 
several different ways. In some cases a hypha forms a typical 
hook, consisting of a binucleate penultimate and a uninucleate 
ultimate and antepenultimate cell. In this case the two nuclei 
of the penultimate cell may fuse to form the nucleus of an ascus, or 
they may divide and give rise to the four nuclei of another hook. 
The uninucleate ultimate cell usually grows down and fuses with 
the antepenultimate cell, after which the nuclei of the two cells 
may give rise to the nuclei of another hook, or they may fuse to 
form an ascus. The walls separating the nuclei may fail to be 
formed without affecting the fate of the nuclei. In this process 
there is a conjugate division comparable to that in the rusts. 
Frequently the ascogenous hyphae do not become markedly 
bent, and in this case, when the two nuclei in the tip divide, a wall 
may separate two pairs of sisters. Either of these pairs may 
divide and give rise to the nuclei of another hook or fuse to form 
the nucleus of an ascus. Any of the methods described above 
by which the number of asci is increased may be repeated many 
- times. 
The relationship of the nuclei which fuse in a plant like Leotia 
is probably of no significance, since they are all in the same plant 
and are probably derived from a single nucleus with the haploid 
number of chromosomes. 
The vegetative hyphae form large storage cells in the hymenium. 
The nuclei in these cells frequently fuse to form a single large 
nucleus. 
The development of the ascocarp indicates that all of its struc- 
