Pythium de Baryanum . 655 
in the greenhouse, and planted in it some cucumber ( Cucutnis 
sativus , L.) seeds. Within two or three days after germination 
of the seeds, some of the seedlings began to droop, the 
tissues softening and yielding near the surface of the soil. The 
prostrate plants were found to be more or less shrunken and 
collapsed at this point, so that on pulling, the plant broke 
easily. The Fungus seems to attack the root and the lower 
part of the stem first, then to proceed upwards, so that in the 
course of a few days the entire plant wilts and finally decays. 
If a portion of the collapsed part of the stem is teased apart on 
the slide and examined under the microscope we can find the 
abundant colourless branched mycelium of the Fungus ex- 
tending in the direction of the axis of the stem, and some- 
times young oogonia can be seen here and there, in the part 
which is much decayed. 
I then took the hypocotyl of the diseased seedlings, usually 
choosing one which was not very much collapsed, and placed 
it in a Petrie dish on moistened filter-paper. After one or two 
days sexual organs are abundantly formed, older stages being 
usually found in the lower part of the hypocotyl which was 
first attacked by the Fungus. Before fixing, small portions 
of the different parts of the hypocotyl were examined under 
the microscope in order to see that a number of sexual organs 
were present in different stages. The suitable portions were 
cut into pieces 5 to 7 mm. in length, and fixed. 
The fixing fluids used were chrom-osmium acetic acid ; 
chrom-acetic acid ; corrosive sublimate in aqueous solution 
both hot and cold ; acetic-sublimate solution in alcohol or 
water ; absolute alcohol ; Carnoy’s fluid, and Merckel’s fluid. 
The first two gave the best results, and the second one was 
more extensively used. 
The material was usually left in the fixing solution from 
fifteen to twenty-four hours, then washed in several changes 
of water for ten or more hours. It was then gradually trans- 
ferred through the usual grades to absolute alcohol. After 
dehydrating it was brought very gradually into xylol or 
chloroform, and transferred with equal care into paraffin, with 
