iQis] BARTLETT—MASS MUTATION 443 



DeVries is in essentials the same.' Another case is provided by 

 0. stenomeres mut. lasiopetala} Heribert-Nilsson' has recently 

 described several new mutations from 0. Lamarckiana ("hetero- 

 game Kombinanten" dependens, undulata, stricta, etc.) which 

 probably show the typical lata type of inheritance, although he 

 erroneously concludes that the repeated segregation of 0. Lamarck- 

 iana from these mutations in each generation is due to the -exist- 

 ence of two types of functioning gametes on the male rather than 

 on the female side. 



It must not be inferred from the similarity of the names that 

 mut. latifolia is a parallel variation to 0. lata DeVries. Such is 

 not the case. Its characters are quite different. Both mut. 

 latifolia and mut. angustifolia will be described and illustrated in a 

 future article. 



As in the case of mut. angustifolia, the progeny of mut. latifolia 

 from the mass mutating strain contained the expected types, f. 

 typica and mut. latifolia, together with the characteristic mutations. 

 The latter did not show differences among themselves which would 

 enable one to classify them as modified typica or modified latifolia, 

 as the case might be. The mother plant belonged to the Fi genera- 

 tion from Lexington E, and showed about the same degree of muta- 

 bility as the typica sister plant, Lexington E-5 (see table II) . The 

 data for mut. latifolia are summarized in table V. 



Mut. gigas. — E. G. Arzberger's discovery that this mutation 

 has 28 chromosomes has already been announced.'" The count 

 has been made only in one plant, Lexington E-5-238 (figs. 5 and 14), 

 belonging to the mass mutant strain. An apparently identical 

 mutation in one of the other strains has appeared this summer 

 (1915), but its heredity is unknown. Mut. gigas is treated, there- 

 fore, as a non-characteristrc mutation. Only 196 seeds were 



' For the latest treatment of these mutations see DeVries, Gruppenweise 

 Artbildung. pp. 244-267. 



' Bartlett, H. H., The mutations of Oenothera stenomeres. Amer. Jour. Bot. 2: 

 100-109. 1915- 



'Heribert-Nilsson, N., Die Spaltungserscheinungen der Oenothera Lamarckiana. 

 Lunds tTniversitets Arsskrift. N.F. Avd. 2. 12: no. i. pp. 132. 1915. 



'" Bartlett, H. H., The experimental study of genetic relationships. Amer. 

 Jour. Bot. 2:132-155. 1915 (seep. 143). 



