Lutz, Triploid Mutants in Oenothera. 



1. 



2. 



3. 

 4. 



5. 

 6. 



Parentage Cult " ral 



number 



0. lata (If)) 5 ) X O. Lnwarrkiauu (14) 



11 11 n )? 



0. Lamarckiana (14) X 0. Lawawkiana (14) 



Fig. 1. 



was again identified in 1910, however, making a total of 8 indi- 

 viduals for the two seasons as follows: 



Cu 

 nu 



6024 

 6027 

 6046 



*> 11 r 6048 



11 ?i 11 n 11 oOol 



O.lata(lb] self-pollinated 5343 



The number of chromosomes of this new 

 form was definitely determined in only three 

 plants, Nos. 2, 5 and 6; root-tip fixations having 

 fortunately been prepared from 2 and 6. The 

 number of figures observed in which the chromo- 

 some number could be clearly ascertained, while 

 not so abundant as in some forms I have studied, 

 left no question as to the certainty of this 

 count. Studies were made from young buds of 

 each representative of No. 4, and the chromo- 

 some number appeared to be 21 in each case, 

 though not definitely ascertained c ). In no one 

 of the 6 individuals did I find any indication of 

 deviation from this number. The chromosomes 

 of the two remaining plants were not examined. 



This mutant was not distinguished from (), 

 Lcui/arrldana in the 1908 cultures until coming 

 to flower, when it attracted the eye, standing 

 among a group of Latnarckianas 1 ), by the greater 

 size of the buds and flowers, deeper yellow of the petals, and, late in 

 the season, by the deeper red of the sepals. In 1910 it was recognized 



Fig. 2. 



the expectation for offspring of this cross, it proved nothing. Since no other mutants 

 were recognized in this cross, and since the two offspring of 0. nanella X ^- ff'ff as 

 differed from the 21-chromosorae mutant in a few points, it is probable that they 

 were true hybrids. However, since the identity of the two plants wa> not clearly 

 established, they must remain unclassified. 



5) The numbers in parentheses indicate the chromosome number typical of the 

 species, and not actual counts. Only 0. lata of No. 6 was studied and determined. 



6) It is usually far more difficult to determine chromosome numbers from the 

 somatic cells of the young buds than from the root-tips, as the figures of the former 

 are usually smaller and the chromosomes more crowded together and less clearly 

 defined. When I relied solely upon bud fixations for these studies, it was a very 

 common experience to fail to determine the count. 



7) Following the precedent of the English translation of ,,Die Mutatioustheoric" 

 I shall form the plural of generic and specific names by the addition of .<, but print 

 in italics as for Latin words. 



*52 



