1921] BLAKESLEE, CARTLEDGE, & WELCH—CUNNINGHAMELLA 195 
but nothing was said about control contrasts between the sub- 
cultures of no. 3, nor of contrasts between the subcultures of no. 21, 
nor is mention anywhere made of uninoculated controls to discover 
what the danger might be from air infection of spores of the oppo- 
site sexes. For aught we know, single spore subcultures of_any 
race might have appeared to produce zygospores when contrasted 
together at the time BURGER made his single spore cultures, which 
was apparently at the end of his series of contrasts with the twenty- 
six races. Neither in these single spore culture contrasts nor in 
any of the others is the abundance of zygospores graded. A single 
zygospore or a limited number which might make the investigator 
suspicious of mixture of strains in his stock culture or of infection 
in his contrast culture apparently have been classified as of equal 
value with our grades A and B 
In a previous paper (12) attention was called to the peculiar 
danger of air borne infection of Cunninghamella when forms of 
this genus had previously been grown in the laboratory. Cunning- 
hamella, it may be remembered, was first described as an Oedo- 
cephalum, a hyphomycetous genus with exogenous spores, but was 
later (2) shown to be a heterothallic mucor by the isolation of its 
sexual races and their combination to form zygospores. It has 
already been shown that another investigator who found zygo- 
spores in his cultures after planting the mycelia from single spores 
Was apparently misled into a theory of hermaphroditism for 
Rhizopus on account of unsuspected infection of his cultures with 
sexual races of the same species. It seems reasonable to suspect 
that BurGER has fallen into a similar error, since he gives no evi- 
dence to the contrary, rather than to believe he has discovered a 
sexual condition unparalleled in the experience of other critical 
workers. 
There are a number of perhaps minor matters in the body of 
BURGER’s paper, such as the use of the terms neutral and zygo- 
tactic, to which objection might be made. Enough has been said, 
however, to indicate that his data do not inevitably lead to 
his main conclusion of pseudoheterothallic hermaphroditism in 
Cunninghamella. 
