1 62 Trow.- — Observations on the Biology and 
due to the treatment with iodine, and resists the action of 
the acid. 
The inner wall then consists of cellulose, and is a mass 
of reserve material. The outer wall consists of two layers, 
a thick inner one, consisting of slightly modified cellulose, 
and disappearing during germination, and an outer thin one 
which is cuticularized and persists as a thin empty shell for 
months after germination has taken place. Other micro- 
chemical reactions lead to the same conclusions. 
The nucleus is always found at rest in nine and ten-day 
cultures, and I have never been able to find more than one. 
The spaces in the protoplasm are very large, corresponding 
in size to the oil-globules present at this stage of development. 
No further changes take place in the oospore other than that 
the protoplasm diminishes in quantity, loses at the same time 
its vacuolated appearance, and takes up a parietal position. 
Germination of the oospores . Karyokinesis. An examin- 
ation of Figs. 52 to 59 will show almost at once the nature 
of the cytological changes which accompany germination. 
The nucleus first of all divides, and the division is repeated 
at the time the inner cell-wall is undergoing dissolution. 
Oospores with four nuclei fix badly for some hitherto unex- 
plained reason, even when the nuclei are apparently in the 
resting condition, so that figures of them have not been 
drawn. The divisions proceed further, and oospores with 
eight nuclei are larger, have a thin cell-wall, and are com- 
pletely filled with protoplasm, the large oil-globules having 
been completely absorbed. A central vacuole forms later, 
and the protoplasm takes up a parietal position. The number 
of nuclei increases to about twenty, and then one or more 
germ-tubes are produced. I have not thought it worth the 
trouble to follow the development of the small sporangia 
in detail. They have been seen in section several times, and 
they presented no peculiarities other than those associated 
with their small size. 
Special attention was paid to the nuclear divisions, and 
although it was difficult to secure positive results, nuclei have 
