1204 Wisconsin Academy of Sciences, Arts, and Letters. 
with the minus strain. The paper cover was replaced, tin foil 
was spread over the top to reduce evaporation, and the appara¬ 
tus was set into the ice box where evaporation would be slow 
and light effects negligible. At the end of six days a line of 
zygospores had formed midway between the two bread bags. 
Thus, as Blakeslee has pointed out, any influence upon the 
origin or direction of growth of the gametophores was not the 
result of any chemical attraction due to the medium or to con¬ 
tact of the mycelial masses, but must have been confined to the 
aerial portions and is, in all probability, restricted to the hyphae 
affected. 
Blakeslee describes the more general morphological aspects 
of conjugation and zygospore formation. In a later paper 
(1906), he describes the germination of the zygospores of 
Phycomyces as well as of several other forms. Germination is 
said to take place after a long period of rest and it is difficult 
to bring the zygospores to germination in the laboratory. In 
the process of germination the outer wall is ruptured and a 
germ tube forms which produces a rudimentary mycelium on 
which are borne sporangia and spores. The spores in turn 
give rise to the next vegetative generation. Presumably it is 
at the time of the formation of the spores in the germ sporangia 
that sex segregation occurs. According to Blakeslee, three 
kinds of spores may be produced in a single germ sporangium: 
the plus, the minus and the neutral, which upon germination 
give rise to the corresponding mycelia. 
The effects of external conditions, as secondary influences 
related to the formation of zygospores in this form, have not 
been carefully investigated by Blakeslee. He secured zygo¬ 
spores on all the substrata tested, which fact disproves the idea 
that oily substances are essential. He obtained them sparsely 
on potato agar but plentifully on potato agar acidulated with 
orange juice. He finds that the zygospores are produced much 
less abundantly in the warm oven, 26°-28°C., than at room 
temperature. 
The writer has verified these results. In securing zygo¬ 
spores, the following media have been used successfully: car¬ 
rots, carrot agar, bean dextrose agar, condensed milk agar, 
potato agar, potato dextrose agar, prune agar, dextrose bouil¬ 
lon agar acidulated with orange juice, bread (both wheat and 
