Some recent work on the cytology of fungus reproduction 
261 
other hand pairs of nuclei are much fewer in number or totally absent 
in the older parts of the mycelium. No other nuclear phenomenon was 
observed which might explain this increase in the number of nuclei. 
Again, the pairs of nuclei reappear in the rapidly-growing investing hyphae 
which arise on the old mycelium and they are present in the wall 
of the perithecium already well developed. Pairs of nuclei, identical 
in appearance with those observed in the other parts of the fungus, were 
found in the young ascogonium and in the various cells produced by the 
septation of the ascogonium. These pairs of nuclei therefore cannot be 
stages in the fusion of female nuclei as has been previously thought but 
are stages of amitotic division. The study of the nuclei of the ascogenous 
hyphae and of the asci was not carried out. This further work will be 
awaited with interest. 
Though Brown and Vallory agree in considering the pairs of nuclei 
in various ascogonia as division stages, the former, as we have seen, 
considers that the division is karyokinetic, whereas the latter holds it to 
be amitotic. 
It is a noteworthy fact that in no case where this fusion of pairs 
of female nuclei has been recorded has there been described a nuclear 
division in the ascogonium, although the nuclei increase greatly in number. 
Especially noticenble is a case like Ascobolus furfuraceus where the asco¬ 
gonium is described as being uninucleate when first formed. 
The phenomenon was first observed in Humeria granulata (Black¬ 
man and Fraser, 1906). The nuclei, which are rather small, show no 
nuclear network but exhibit a nuclear membrane and a deeply staining 
nucleolus. “As development proceeds the nuclei increace only slightly in 
size but enormously in number. Female nuclei were observed 
fusing in pairs in the ascogonium. These fusions ars to be observed in 
ascogonia of various ages. No data were obtained as to the 
number of nuclei in the ascogonium at its first inception, but judging 
from the size of the organ at that stage and from the relatively small 
number of nuclei in the vegetative cells, very numerous divisions must 
take place. It is curious that such divisions were never observed in the 
ascogonium; it is probable that they are intermittent in occurense; possibly 
they take place only at night“ It would seem from these extracts that 
the authors must have considered the case for nuclear division and decided 
against it. 
In the Laboulbeniaceae (considered by Thaxter and Faull as 
belonging to the Pyrenomycetineae) Faull (1911) has published an intro¬ 
ductory account of the cytology of the group. The female organ (pro¬ 
carp) consists of three distinct parts. The uppermost portion is the 
trichogyne and may be unicellular or more complicated in structure; the 
middle portion is in all cases unicellular and uninucleate and is termed 
the trichophoric cell; the lowest portion, unicellular and uninucleate, is 
termed the carpogonium, being the portion of the procarp which is ferti¬ 
lised. Except in the case of Laboulbenia chaetofhora , the author is un¬ 
certain as to the origin of the pair of nuclei which appear later in the 
carpogenic cell. This species is interesting because of the lack of anthe- 
ridia or of any organs that might function as antheridia. The nucleus of 
the carpogonium divides and the lower of the two daughter nuclei is cut 
off to form the inferior supporting cell. The nucleus in the trichophoric 
