588 Brooks .— The Development of 
of the hyphae occur frequently when they intrude between the host cells. It 
is often observed that cells of the parasite are very closely attached to cells 
of the host. In such cases it appears that the wall of the fungus cell becomes 
somewhat gelatinized so that the contact can be more intimate. Haustoria, 
however, were never seen. After a time the host cells, which are in intimate 
contact with the fungus, shrivel and die. Such disorganization of the host 
cells is seen particularly well where a branch of the general mycelium pene¬ 
trates the palisade region of the leaf. It is obvious that the fungus kills the 
host cells gradually. On the other hand, the parasite does not remain 
in intimate connexion with living cells of the host over such a long period 
of time as is the case with Rust Fungi, where, of course, haustoria are 
developed. The chlorophyll granules of the cells of the Cherry leaves 
in the neighbourhood of the mycelium are smaller in size than granules in 
healthy parts, and they are yellowish in colour. 
On cutting hand sections of fresh material, it is seen that the hyphae of 
the parasite are filled with extremely granular protoplasm. In stained 
preparations the cells are found to be multinucleate, as will be seen by 
an examination of Fig. i. Some cells contain as many as fifteen nuclei, but 
the general number is from five to eight. The multinucleate nature of the 
cells of this fungus is thus the same as that found in Humaria granulata (3), 
Aspergillus herbariorum (20), and many other Ascomycetes, though different 
from the uninucleate condition of the cells in the Mildews (22). It is very 
doubtful, however, whether any phylogenetic significance is to be attributed 
to the uninucleate or multinucleate nature of vegetative cells in the Asco¬ 
mycetes. 
The nuclei of Gnomonia erythrostoma are small, but, in spite of this, 
they show a fair amount of structural detail—much more in fact than the 
vegetative nuclei of many other fungi as yet examined. The vegetative 
nucleus contains several small, deeply staining, granules found generally 
near the nuclear membrane, and in some cases a distinct though faint 
reticulum can be seen (Fig. 2) ; a nucleolus may or may not be present. In 
many other fungi (e. g. the Rusts), the only portion of the vegetative nucleus 
which takes up the stain with ease is the nucleolus, so that, apart from the 
latter, the nucleus appears homogenous. 
Apart from the divisions in the ascus and ascospore to be described 
later, the nuclei have been only rarely seen undergoing the process of 
division, and in these cases details could not be made out. 5 
After the mycelium has ramified in the leaves for some weeks, spermo- 
gonia and the coiled structures (Knauel verflochtener Faden) described by 
Frank are formed. Although the two sets of structures overlap in develop¬ 
ment, some spermogonia always appear first. 
