Frey—Physiology of Venturia Inequalis. 
307 
nucleus. He believes that this fusion, since it involves more than 
two nuclei, is not sexual. The ascus is a new structure, the prod¬ 
uct of the asexual generation. The spores are cut out of the cyto¬ 
plasm by kinoplasmic radiations from the central body. Harper 
found that reduction occurs in the first division of the ascus nucleus 
of Erysiphe communis. 
The process of spore formation is similar in Peziza stevensonia 
and also in Ascoholus furfuraceus. The kinoplasm forms the spin¬ 
dle fibres and the astral radiations which cause the delimitation of 
the spores. The nucleus may be active in directing the process of 
spore delimitation as it moves to the periphery of the ascus. The 
central body may be only a distributing point of nuclear activity 
although it appears to be able to form new kinoplasmic fibres by 
its own activity. The nature of the kinoplasmic changes in form¬ 
ing a cell wall are not known. The chromosome number does not 
change but there seems to be a reduction in quantity. The chromo¬ 
somes always remain attached to the central body by fibres. 
Harper (1899) studied spore formation in the sporangia of cer¬ 
tain Phycomycetes. Brefeld (1873) held that the jelly of the 
Mucorineae, in which asexual spores are imbedded, is homologous 
with the epiplasm of the ascus, and that the sporangia of the 
Zygomycetes illustrate an ancestral type from which the ascus has 
developed. Harper’s results utterly failed to corroborate Brefeld’s 
theory. In Synchytrium, Pilobolus and Sporodinia the spores are 
cut out by progressive cleavage of the cytoplasm, as a result of 
which all the cytoplasm of the sporangia is used in the formation 
of the spores. There is, therefore, no structure in the molds com¬ 
parable with the epiplasm of the ascus. Spore formation in the 
ascus of Lachnea scutellata was found to be similar to the corre¬ 
sponding process in Peziza stevensoniona and Ascoholus furfuraceus 
except in slight details. The process in Sporodinia is spore forma¬ 
tion by progressive cleavage; the process in Lachnea scutellata is 
free cell formation. 
Tulasne (1866) had observed a fusion of oogone and antheridium 
by means of pores in Pyronema confiuens. De Bary (1863) could 
not find the actual fusion,’ though he felt certain that it' occurred. 
Harper (1900) figures an oogonium of Pyronema confiuens with a 
trichogyne applied to the antheridium. At the point of application 
of the trichogyne to the wall of the antheridium a pore is formed 
by dissolution of the cell walls. The nuclei of the antheridium pass 
into the trichogyne and through a pore in the wall separating the 
