276 Trow, — Observations on the Biology and 
not differ from the extramatrical in any material way. Both 
may bear the reproductive organs. There is no differentiation 
of rhizoids or haustoria. 
The details of the life history were worked out almost 
entirely with the help of the moist-chamber cultures. This 
was necessary not only as a means of determining the system- 
atic position of the species, but especially as a guide to the 
proper sequence of the series of sections required to illustrate 
the karyology. 
No attempt will be made to describe the results in the order 
in which they were obtained, but rather in the way in which 
they can be most easily followed, and in the order in which 
they could most quickly be verified. 
Germination of the conidia. The conidia are either ter- 
minal and spherical or intercalary and barrel-shaped. If they 
are placed in distilled water they remain at rest for an 
indefinite period. If placed in a drop of cabbage water they 
germinate at once, one or more germ-tubes putting in an 
appearance with the greatest punctuality in about an hour’s 
time. So regular is this that if thousands of conidia are 
sown at the same time it is generally impossible to find a 
conidium with a germ-tube three-quarters of an hour later, 
or a conidium without one after two hours. Germination 
likewise takes place if a fly-leg is added to a drop of tap- 
water containing conidia, but not quite so regularly. Figs. 
1 and % (PL XV) fully illustrate the process in the case of two 
conidia which were placed in cabbage-water at 9.50 a.m. 
The germ-tube makes its appearance very suddenly, and its 
apex is filled with hyaloplasm. Sometimes, as in Fig. 1 b , an 
elongated vacuole makes its appearance, and then germ-tubes 
generally appear opposite its poles. In a few cases there have 
been observed faint indications of a segmentation of the 
protoplasm, as if zoospores were to be formed. No zoospores, 
however, have been seen at any time, and it may be regarded 
as certain that the conidia are no longer capable of producing 
them ; for (1) there is no indication of a terminal beak such 
as is usual in sporangia, (2) no germination takes place in 
