152 ; A. W. BENNETT. 
the facility with which its cells become detached, the disin- 
tegration advancing from the base towards the apex. The 
detached cells are usually cylindrical, but may assume the 
most various forms—spherical, fusiform, oval, &c. ; this change 
of form being especially prevalent when the mycelium is 
transferred to a new nutrient fluid. 
In addition to the form of Chalara Mycoderma now de- 
scribed, another variety, or possibly a different species, was 
observed in pellicles of yeast that had remained undisturbed 
for a considerable time where the nutriment was abundant, 
and was characterised by being composed of much stouter 
cells more firmly united. The separation of conidia takes 
place in this form only from terminal cells ; and they remind 
one, from their crowded and erect position, of a pencil of 
Penicillium. The tendency of the cells to become detached 
from one another appears then to be confined to this sepa- 
ration of conidia. No intermediate forms were observed 
between the two varieties, nor could one be transmuted into 
the other. 
As far as the cycle of development of Chalara is at present 
known, it is completed by the formation and germination of 
the conidia, They usually develop into oval or cylindrical 
cells in which state they remain if the amount of nutriment 
is insufficient ; but when transferred into a fresh nutrient fluid, 
they put out after some hours long filaments, which develop 
according to circumstances into connected mycelia, or break 
up into cylindrical cells from which conidia are detached. 
The development of the pellicle can be best watched on 
infusions in which various vegetable substances, especially 
fragments of roots, are decaying under water. When access 
of air is unimpeded, it commences to appear in a few days in 
the form of isolated branching cells mixed with cylindrical 
bent mycelial cells either detached or united into stars or 
zig-zag rows, or the whole field of view is occupied by 
parallel filaments (fig. 9, a, 6). The cells vary greatly in 
diameter as well as in the nature of their contents. Very 
often they contain a number of vacuoles, enclosing particles 
of protoplasm, which closely resemble nuclei. ‘* Buds”? of 
various lengths, are then formed at the ends of particular cells 
which then separate as detached cells; and filaments are also 
produced, many of the cells in which are empty. The more 
conspicuous the pellicle the smaller is the proportion of the 
branching mycelium, the larger the proportion of the arbo- 
rescent form. The branching mycelium appears to belong 
mainly to Mycoderma, the arborescent form usually to 
Oidium lactis, less often to Chalara. ‘The slenderer filaments 
