19 iq] burger— CUNNINGH AMELIA 141 



spores with nos. 3, 13, and 20, all 3 of which also formed 

 zygospores in series B with no. 21, which in series A was shown 

 to be minus. Since then, as determined by contrast with no. 21 

 in series B, nos. 3, 9, 13, and 20 are all plus, we have the anomaly 

 of a plus strain no. 9 conjugating with 3 other plus strains, nos. 

 3, 13, and 20. 



If we assume, as shown in series A and series B, that nos. 21 

 and 9 are minus and plus respectively, cultures i, 2, 3, 7, 9, 10, 

 13, 14, 16, 17, and 20, since they react with no. 21, would be 

 minus, and nos. 3-8, 12, 13, 15, 20, and 21, since they react with 

 no. 9, would be plus. The other cultures, 22-33, which did not 

 conjugate with either 21 or 9, must, according to Blakeslee, be 

 considered as neutrals or as belonging to a different species. Cul- 

 tures 3, 7, 13, and 20, on the other hand, must be hermaphroditic, 

 or sexually bivalent, since they are able to conjugate with both 

 plus and minus strains. 



CONTRAST SERIES D 



In this series culture 14, which was shown to be plus in series 

 B, was contrasted with all the other cultures of C. hertholletiae 

 and formed zygospores with nos. 3, 4, 7, 8, 12, 13, 16, 20, and 21. 

 In series B cultures 9 and 14 were both shown to be plus. If 

 these 2 cultures are plus, that is, if they are of the same sex, they 

 should behave in the same manner when contrasted with all the 

 other cultures. As a matter of fact, however, we see that no. 9 

 formed zygospores in series C with nos. 3-8, 12, 13, 15, 20, and 21, 

 while in the present series culture 14 showed no sexual reaction 

 with cultures 5, 6, and 15, but formed zygospores with 16. Since 

 culture 9 does not form zygospores with the same cultures as no. 14, 

 they cannot be regarded, therefore, as sexually identical. 



CONTRAST SERIES E 



Culture no. 7 was next used and formed zygospores with nos. 

 9, 10, 14, 16, 17, 20, and 21. This culture was shown to be plus 

 in series B when contrasted with no. 21, and here again we notice 

 a selective power, the reactions of this plus strain not conforming 

 in all respects to the 2 plus strains employed in contrast series 

 C and D. 



