1921] BLAKESLEE, CARTLEDGE, & WELCH—CUNNINGHAMELLA 189 
has been made for four species of Cunninghamella, the details of 
which will be given later. Since they offer no support to BURGER’s 
conception of hermaphroditism in the genus, and since his cultures 
were allowed to die out before his final results were published, 
making it impossible for his material* to be retested, it is necessary 
to subject both his experimental technique and conclusions to — 
searching criticism in lieu of other means of judging of the correct- 
ness of a statement which runs counter to the experience of most 
careful workers on the Mucorineae. BURGER’s paper will be con- 
sidered before discussing the results of this investigation. 
BurGER found great irregularity in the sexual behavior of races 
of C. bertholletiae. While some races were consistently either plus 
or minus-in reaction, others appeared to react both as plus and 
minus with properly chosen test strains. Certain races seemed to 
form a sexual triangle. His race A, for example, would form 
zygospores with B, race B would form zygospores with C, race C 
would form zygospores with A, and the family triangle was complete. 
BURGER’s conclusions are based primarily upon tests with 
twenty-six? races of C. bertholletiae. Since he says ‘authentic 
cultures of C. bertholletiae and C. elegans were obtained from 
Holland,” and later credits us with having sent the only race of 
C. elegans which he used in his tests, there is little doubt that his 
race no. 21 of C. bertholletiae is identical with the no. 213 which we 
secured from the Centralstelle, and of which we sent a subculture 
to the Harvard laboratory with C. elegans shortly before BURGER 
used the strains in his investigations. In addition to these two 
races, he used the plus and minus strains of C. echinulata and of 
Mucor V, which had also been sent by us to the Harvard laboratory. 
The sexual races of these two species were contrasted with all his 
twenty-six races of C. bertholletiae, but without finding any “imper- 
fect hybridization” reactions. The race of C. elegans and six races 
of C. bertholletiae were individually contrasted with the remaining 
races of a collection consisting of twenty-six races of C. bertholletiae, 
five races of C. echinulata (including our plus and minus strains), 
2 Except his race no. 21, which will be discussed later. 
3In two places in the text (probably through error), his race no. 25 is called 
Mucor V minus. 
