168 BOTANICAL GAZETTE |S EPTEMBER 
mycelia met sooner in their growth at one end of the line of contact 
than at the other, and thus offered a greater area at a given time 
for the observation of sexual reactions which may soon be covered 
by the later growth of the mycelium. Obviously the angle of the 
V must be left open, and care taken in planting a tester to avoid 
touching with the needle the previous. line of inoculation. The 
distance between the points or lines of inoculations may be a matter 
of some importance, since certain forms fail to produce zygospores 
in the line near the inoculations, while others produce them only 
within a distance of a few millimeters from the inoculations. 
After inoculation, the stacks are stored in the incubating oven 
if greater than laboratory temperature is necessary. If the stacks 
are inverted until the mycelium covers the agar, the danger is 
avoided of water condensing on the dishes above and falling upon 
the cultures, with a consequent running together of the recently 
made inoculations. It may be found desirable to have jars of 
water on the culture shelves to prevent the nutrient from drying 
out before they are finally recorded. Before the cultures had 
matured, they were inspected to see whether any inoculation had 
failed to grow. With Cunninghamella the inspection was more 
thorough than with most other forms, and consisted in an exami- 
nation for beginnings of conjugation such as are seen in “imperfect 
hybridization.”” Apart from this early inspection on the first or 
second day after inoculation, and before there is much danger in 
disseminating spores from the cultures into the air, the stacks were 
not opened before being sterilized in the autoclave, generally on the 
seventh or eighthday. The heat of the autoclave melts the agar and 
tends to glue the filaments to the bottom of the dish above. It 
_ was found convenient, therefore, to have the stacks inverted during 
sterilization, with a pan below to catch the melted agar. Just 
before cooling the stacks were erected and each dish lifted in succes- 
sion. Any of the cultures still adhering to their covers after this . 
procedure may be freed by the use of alcohol. Keeping the dishes 
closed while the spores are likely to be shed reduces the amount of 
infection of the laboratory air, which is probably impossible to 
prevent entirely when a species like Cunninghamella or Syncephalas- 
trum is cultivated in a wholesale manner. Fig. 1 shows a series 
