iqiq] burger— CUNN inch am ELLA 143 



CONTRAST SERIES H 



Each of the single-spore cultures of no. 3 were contrasted 

 with each of the 2 pure cultures of no. 9, and in every case normal 

 zygospores were produced, although both nos. 3 and 9 were shown 

 in series B to be plus. 



CONTRAST SERIES I 



Each of the 3 sub-cultures of no. 3 were contrasted with each 

 of the 4 cultures of no. 21, and every contrast plate produced 

 normal zygospores, although the latter had been shown to be 

 minus in series A. 



CONTRAST SERIES J 



The 2 sub-cultures of no. 9, which was shown to be plus in 

 series B, were contrasted with each of the 4 sub-cultures of no. 21, 

 and each contrast plate produced normal zygospores. It is dem- 

 onstrated, therefore, beyond question that cultures 3, 9, and 21 

 form zygospores with both plus and minus strains, and therefore 

 are sexually bivalent or hermaphroditic. Single-spore cultures 

 were made from these 3 strains to eliminate the objection that 

 the cultures had been mixed. Each of the cultures, obtained from 

 a single spore, from either strain formed zygospores with the 

 single-spore cultures of the other 2 strains, thereby confirming 

 the results of the previous contrast series. 



In the above contrast series, nos. i and 2 have always remained 

 constantly plus, while nos. 4-6, 12, 15, 18, 19, 22-26 were always 

 minus. Nos. 3, 7-11, 13, 14, 16, 17, 20, 21, and 34, however, have 

 reacted with both the so-called plus and minus strains. Those 

 numbers which showed no sexual reaction with any of the strains 

 of C. bertholletiae are nos. 27-33, ^^^ therefore, according to the 

 accepted terminology, are neutrals. We must remember, however, 

 that it was pointed out before that cultures 27 and 28 are C. 

 echinulata plus and minus as separated by Blakeslee. These 2 

 cultures always formed normal zygospores when contrasted with 

 each other, and therefore are not neutrals. Cultures 32 and :i,^ 

 are Mucor V. minus and plus as separated by Blakeslee; these 

 cultures also formed normal zygospores when contrasted with 



