f.">4 Liitz, Triploid Mutants in Oenothera. 



having first ascertained the number in each parent) to determine 

 whether 14- and 28-chromosome offspring are occasionally produced. 

 Also in O. fjigcis X O. Lamarcl-inim to determine whether 42-chro- 

 mosome offspring may occasionally result from this cross. 



6. Extensive tests for apogamy in Lamarckiana, Ictta, yiyfts etc. 



In order to obtain a large number of figures in metaphase 

 (which is the only satisfactory stage for the exact determination 

 of somatic chromosome number), root-tip fixation should be prepared 

 between the hours of 10 A.M. and 12 : 30 P.M. It is desirable to 

 make seven or eight fixations from plants with a large number 

 of chromosomes. 



It will be of great benefit to the reader if all workers report- 

 ing upon cell studies of the Oenotheras in the future will clearly 

 state, not only the number of individuals in which chromosome counts 

 have been approximately determined, but the number in with these 

 counts have been certainly ascertained. Definite statements as to 

 whether the plants have been derived from open or guarded pollina- 

 tions, together with some simple and precise description of the 

 vegetative characters of the plants in question, will be of great 

 assistance to other workers. 



It has been my great privilege to prepare this report in consulta- 

 tion with Professor V. Gregoire, and I am most deeply indebted to 

 him for many suggested interpretations and lines of thought leading 

 ultimately to the demonstration of the harmonious relationship 

 existing between practically all of the observed phenomena thus 

 far reported for the germ and somatic cells of Oenothera. 



April 9. 1912. 



Literature cited. 



1. Blariughem, L., Revue Scientifique, Feb. 24, 1912. 



2. Davis, B. M., Pollen Development of Oenothera grandiflora. Annals of Botany 



XXIII: 551571. Pis. XLI-XLII. 1909. 



3. The Reduction Divisions of Oenothera biennis. Annals of Botany XXIV: 

 (531-651. Pis. LII LIII. 1910. 



4. A Comparison of the Reduction Divisions of Oenothera Lamarckiana and 

 0. gigas. Annals of Botany XXV: 941974. Pis. LXXI LXXII. 

 1911. 



5. De Vries, Hugo, Die Mutationstheorie. Bd. I, 1901. Bd. II, 190203. 



'i. Bastarde von Oenothera gigas. Berichten der Deutsch. Botan. Gesellsch. 



Bd. XXVIa, Heft 10: 754-762. 1908. 



7. Gates, R. R., Pollen Development in Hybrids of Oenothera lata^ 0. Lamar- 

 ckiana and its Relation to Mutation. Botanical Gazette XLIII : 81 115. 

 Pis. II IV. 1907. 



Hybridization and Germ Cells of Oenothera Mutants. Botanical Gazette 

 XLIV: 1-21. Figs. 3, 1907. 



!). The Chromosomes of Oenothera Mutants and Hybrids. Internat. Zoologic. 



Congress, Boston, August 19. >7. 

 10. The Chromosomes of Oenothera. Science N.S. XXVII: 193195. 1908. 



