i 9 o8] GATES—REDUCTION IN OENOTHERA 31 



5. It is suggested that there is probably a direct relation between 

 the events of reduction in a given genus and its variation, as well as its 

 hybridization phenomena. 



I desire to express my thanks to Professors John M. Coulter 

 and Charles R. Barnes for valuable suggestions and adequate 

 facilities in connect'on with this work. 



The University of Chicago 



LITERATURE CITED 

 1. Allen, C. E., Nuclear division in the pollen mother cells of Lilium canadense. 



Annals of Botany 19:189-258. pis. 6-g. 1905. 

 2. , Das Verhalten der Kernsubstanzen wahrend der Synapsis in den 



Pollenmutterzellen von Lilium canadense. Jahrb. Wiss. Bot. 42:72-82. 



pi. 2. 1905. 

 3. Berghs, Jules, La formation des chromosomes heterotypiques dans murs la 



sporogenese vegetale. I. Depuis le spireme jusqu'au chromosomes murs, 



dans la microsporogenese d' 'Allium fishdosum et Lilium lancifolium (speci- 



osum). La Cellule 21:173-189. pi. 1. 1904. 



4- _ — , II. Depuis la sporogonie jusqu'au spireme definitif, dans la micro- 

 sporogenese de Y Allium fistidosum. Idem 21:383-397. pi. 1. 1904. 



5- - — ,111. La microsporogenese de Convallaria maialis. Idem 22:43-50. 

 pi. 1. 1905. 



6. - — , IV. La microsporogenese de Drosera rotundifolia, Narlhecium 

 ossifragum, et Helleborus foetidus. Idem 22:141-160. pis. 2. 1905. 



7. Cardiff, Ira D., A study of synapsis and reduction. Bull. Torr. Bot. 

 Club 33:271-306. pis. 12-15. !9o6. 



8. Farmer, J. B., and Moore, J. E. S., New investigations into the reduction 

 phenomena of animals and plants. Proc. Roy. Soc. 72 : 104-108. figs. 6. 1903. 



9- — — > On the maiotic phase (reduction divisions) in animals and plants. 

 Quart. Jour. Micr. Sci. 48:489-557. pis. 34-41. 1905. 



10. Farmer, J. B., and Shove, Dorothy, On the structure and development of 

 the somatic and heterotype chromosomes of Tradescantia virgin ica. Idem 

 48:559-569. pis. 42, 43. 1905. 



11. Gates, R. R., Pollen development in hybrids of Oenothera lata X O. 

 Liimarckiana, and its relation to mutation. Bot. Gazette 43:81-115. 

 pis. 2-4. 1907. 



12. - — , Hybridization and germ cells of Oenothera mutants. Idem 44: 1-21. 

 figs. 3. 1907. 



13- ~ — , International Zool. Congress, Boston, Aug., 1907. 



14- , The chromosomes of Oenothera. Science N. S. 27:193-195. 1908. 



15- , Further studies on the chromosomes of Oenothera. Idem 27:335. 



