322 Wisconsin Academy of Sciences, Arts, and Letters. 
quantities of food material proceed to divide, and before the nuclei 
can migrate another division occurs. This accounts for the figures 
observed by Clausen. There is, therefore, no significance to be at¬ 
tached to nuclei in this condition. In poorly nourished mycelia the 
paired nuclei are absent, as the nuclei have time to move apart 
before another division takes place. 
Killian (1915) described the origin of the archicarp in Venturia 
inaequalis. He finds that a single coiled hyphae enlarges in the 
perithecium and forms an ascogonium. A trichogyne is produced 
which protrudes from the perithecium and grows toward the 
antheridium, but remains surrounded by a layer of cells. The two 
organs come into contact and pores are formed through which the 
male nuclei pass into the trichogyne. The walls of the ascogone 
are dissolved and the male nuclei pair with the female nuclei and 
aggregate in the end or basal cells of the ascogonium. Further ob¬ 
servations were not made as the organism offers considerable diffi¬ 
culty for study. 
Cryptomyces pteridis represents a type in which the trichogyne 
no longer functions. Pairing of equivalent cells in the fruiting 
body occurs and one of the cells may be regarded as an egg. The 
nucleus from the male cell migrates into the oogonium through a 
pore, but fusion with the egg nucleus does not take place for some 
time. The cell containing the egg does not produce ascogenous 
hyphae, although it elongates in an attempt to do so, but itself be¬ 
comes the ascus. The process is essentially like that described by 
Guilliermond for yeasts. Only one nuclear fusion occurs. 
The phylogeny of the Ascomycetes has been the subject of con¬ 
siderable controversy. Sachs (1868) and de Bary (1870-1899) 
noted the similarity of the sex organs of the Ascomycetes and the 
Plorideae. Brefeld (1875) held that the Ascomycetes were derived 
from the Phycomycetes. He believed the sporangium evolved into 
an ascus, a view which Harper’s work has shown to be extremely 
improbable. De Bary, (1881-84) states that the Ascomycetes may 
have originated from the Peronospora. He suggests that certain 
forms like Eremascus may have been derived from the Mucorales. 
Bucholz (1912) states that Endogone is a Phycomycete. The 
structure developed from the fusion of two unequally differentiated 
sex cells he designates a ^^zygosporocarp”. Clausen (1912) pre¬ 
fers the view that the Oomycetes gave rise to the Ascomycetes 
Dodge (1914) in a very able discussion of the literature concludes 
