1921] BLAKESLEE, CARTLEDGE, & WELCH—CUNNINGHAMELLA 211 
‘ TABLE VIIl—Continued 
o.60:90 00 
A. INTRASPECIFIC REACTIONS daa atay 
GRADE RACES Minus testers pooping Plus testers Minus testers Dob net 
266 1457 1459 |213 |183 |241 [18 5 145 7 |227 |268 |234 |464 |456 |188 lass |260 |ror |515 
Minus races 
od ay ets eee 01-010) OFOLO1. OL 0OLObe Ol OL OLOT OO; c 
al ik 7. Oat GO| OG rOrOLOLOVOL@Ord] OFOLoTrda-O7.. c 
cs ay Die ee ea O; OPO; OF OF OPO) OVore 1010; 01T0Lro}:. c 
cael = Wen ce O| O} O} O} OF O} O} O} O} d}| O}| O| O} dj O}.. a 
cc ae Br ce eke ages QO} 0; OF OO] OO] CO] GO; OC] 07 OF 0] Oi cc EOT.. O 
Sy (all iy © Con O} OFO} 07 O10 0} Gl -d70] 01 01 DI Ol... c 
Grades (all com} %/3/2/8/S/5/ 3/8/18) siaislsisis 
tions) egg alalalalxals ° ° adel ew |e oe ° 
the same species, if any reaction was initiated at all, it was carried 
through to the production of zygospores, except of course for some 
obviously detrimental check in environmental conditions. The 
sexual process resulting in the production of zygospores may be 
considered the sum of two distinct reactions; first, the formation 
of opposed progametes or at most gametes; second, the dissolution 
of the cross walls between the gametes and the growth of the 
fusion cell into a zygospore. Only the first reaction can take place 
when the plus and minus races contrasted belong to different 
species.5 
A number of facts indicate, however, that in the races listed 
under C. bertholletiae we are dealing with a single species. The 
essential uniformity of the strains in morphological appearance 
speaks for specific identity, and the production of zygospores fails 
to separate them into any consistent groups. A quadrangular 
reaction within selected groups of four may be discerned from 
table VII A. Thus the same four races shown in fig. 1 form the 
following quadrangle, in which Z stands for zygospore formation, 
H for imperfect sexual reaction, and O for no sexual reaction. Other 
similar quadrangles may be assembled from table VIIA. The fact 
that only imperfect reactions are found in certain contrasts when 
True hybrids have been reported between closely related species of Mucor by 
Sarto and NAGANISHI (19). 
