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pair ol sperm Icllials, halaiicftl by a pair of c^K Iclliais, which 

 accoLiiil for ihc iiiilikciiess of reciprocal hybrids. In holli lyjjes 

 the result is the inaintenance of (riie-hree.ling species, all the 

 individuals of which are uniformly hetenjzygous. The demt>n- 

 sl rat ion of (he existence of these lethal factors has been possible 

 because of the linkage between the lethals and other factors 

 which give rise to visible characters, and the occurrence of cross- 

 ing over which has separated and recombined the lethals in new 

 combinations with the other known factors. 



Including these balanced lethals, 13 factors are recognized as 

 belonging to a single linkage group. 



Two factors have now been found which are independent of the 

 large linkage group; one of these is the short-styled hrevistylis 

 discovered by de Vries, in nature, at the beginning of his work 

 40 years ago, but not yet discovered in experimental culture 

 except as recessive segregates from previous crosses. The 

 second is the "old gold" factor which is not only independent 

 of the big linkage group, but also independent of brevistylis, 

 giving in crosses with the latter, the typical dihybrid Mendelian 

 ratio, 9:3:3:1, regardless of the presence or absence of the 

 lethals or of other factors belonging to the big linkage group. 



Slides were shown illustrating the new double-flowered 

 mutant form, mut. supplena, which originated last summer in 

 the lecturer's cultures, being the first double-flowered Oenothera 

 which has been reported. This mutation was repeated eight 

 times in one culture and was associated with three different 

 vegetative habits which were recognized as being differentiated 

 from one another in the number of lethal factors present. This 

 is taken to indicate the probable independence, or near inde- 

 pendence, of the supplena factor from the big linkage group, but 

 this conclusion is tentative and awaits critical evidence from 

 the coming summer's cultures. 



Arthur H. Graves, Secretary. 



NEWS NOTES 



The Bulletin of the Torrey Botanical Club which has formerly 

 been issued in twelve numbers a year has been changed to nine 

 numbers, none being published during July, August and Septem- 

 ber. There will be no decrease in the total pagination for the 

 vear. 



