FUNGI 
213 
0.1 per cent solution of leucin, or into a 0.05 to 0.1 per cent solution of 
haemoglobin. Begin to examine after 24 hours. 
Oogonia have been produced in great numbers by the following 
method: cut ordinary corn (Zea Mais) into small pieces and boil for 
20 minutes. When cool, put pieces into a Petri dish and add enough 
pond water to nearly cover the pieces of corn. Oogonia may appear 
within 3 or 4 days. 
For fixing, the following formula is excellent for material which 
is to be mounted whole: 
Formalin. 10 c.c. 
Glacial acetic acid. 5 c.c. 
Water. 85 c.c. 
Fix at least 24 hours, but material may be left for months in this 
fixing agent. 
Stain some in Magdala red and 
anilin blue, and some in iron-alum 
haematoxylin. Mount some of each 
lot on each slide (Fig. 54). 
For sections, it is better to fix in 
the special chromo-acetic-osmic-acid 
solution. 
Satisfactory material for general 
laboratory purposes can be secured 
as just described. Absolutely pure 
cultures can be secured only by observ¬ 
ing all the precautions necessary in 
bacteriological work. 
Achlya is similar and equally good 
for illustrative purposes. It is found 
on insects, fishes, dead fish eggs, and 
on algae. The zoospores escape in a 
mass, which, for a short time, is held 
together by a transparent pellicle; in 
Saprolegnia the zoospores swarm sepa¬ 
rately. In Saprolegnia , the new spor¬ 
angia grow up through the empty ones; 
in Achlya , the later sporangia arise on lateral branches below the 
earlier ones. Dictyuchus and Olpidium often appear when one is 
Fig. 54. — Saprolegnia: A, sporan¬ 
gium; in B and C the upper cell is an 
oogonium; the cells below are probably 
sporangia. The material was grown 
on flies by Miss Mary Norton at mid¬ 
dle Granville, New York, and was fixed 
in formalin acetic acid and stained in 
Magdala red and anilin blue. X150. 
