1907] GATES— HY BRTDIZATION OF OENOTHERA MUTANTS 



21 



doubt, and until their mode of origin is ascertained no significance can 

 be attached to them. 



3. In the telophase of the heterotypic mitosis in the pollen mother 

 cells of the Lamarckiana hybrid, the chromosomes frequently have 

 distinctly the form of tetrads. In the homotypic mitosis of O. 

 Lamarckiana^ as well as in the somatic mitoses (in various floral tis- 

 sues) in all forms studied, the chromosomes are two-lobed in the telo- 

 phase- The tetrad appearance is probably due to the same lobing 

 of the bivalent chromosomes that takes place in the telophase of the 



homotypic and somatic mitoses* 



This investigation has been carried on under the supervision of 



Professor John M, Coulter and Dr. Charles J. Chamberiain, 



The University of Chicago 



