146 BOTANICAL GAZETTE [august 



Summary 



1. In Cunninghamella there does not exist sexual dimorphism. 



2. C. echinulata plus and minus, or Mucor V. plus and minus 

 as separated by Blakeslee, are unable to form progametes or 

 gametes when contrasted with any one of 26 cultures of C. herthol- 

 letiae. 



3. Many of these cultures of C. bertholletiae were able to form 

 zygospores when contrasted with certain other cultures of this 

 same species. 



4. There exists a selective power in some strains to form 

 zygospores with certain other strains. This condition of pseudo- 

 heterothallism cannot be explained at present. 



5. There exists a condition in some strains which might be 

 called hermaphroditism. 



6. In none of the hermaphroditic strains did branches of the 

 same hyphae conjugate. 



7. Zygospores were produced only when 2 strains were con- 

 tracted whose gametes were compatible. 



I wish to express my gratitude to Professor Thaxter, under 

 whose direction the work was undertaken, also to Dr. Blakeslee 

 and Mr. A. R, Butler for various cultures used in this study. 



Harvard University 

 Cambridge, Mass. 



