118 
PHYSICS: A. F. BLAKESLEE 
Proc. N. A. S. 
Two plants which were changing over from a normal to a Quercina con- 
dition were investigated with regard to the type of offspring obtained from 
their individual capsules. There seems to be only a rough correspondence 
between the strength of the Quercina character in the parent and the 
number of Quercina plants in its offspring. 
As has been stated already, Quercina flowers are characteristically de- 
void of pollen. In a few plants, however, which were becoming trans- 
formed into Quercinas, pollen was obtained and used in crosses onto normal 
plants. Quercina offspring were obtained from such crosses showing that 
the character in question can be transmitted through the male. 
The non-Mendelian nature of the breeding results with Quercina plants 
as well as the spontaneous occurrence of the character on branches of 
normal plants and its spread to the new growth suggested the desirability 
of attempting to transmit the character by grafting. This attempt was 
entirely successful and Quercina cions grafted onto normal plants of the 
Jimson Weed causes the new growth of the stock to take on the appear- 
ance of Quercina. There is ample evidence, therefore, to indicate that the 
cause of the Quercina complex, which by ourselves as well as by earlier 
investigators had been supposed to be a manifestation of a genetic char- 
acter, is in fact a disease transmissible by grafting. 
It has not been found possible to infect plants artificially by rubbing 
with diseased leaves nor by inoculation of expressed juice from Quercina 
plants. 
The profound morphological changes brought about in the leaves and 
especially in the flowers and fruit are such that Quercina individuals would 
be considered worthy of specific if not of generic separation if 100 per cent 
of the seedlings instead of only 79 per cent came true to the Quercina com- 
plex. As the facts stand, however, there is much in the behavior of 
Quercina plants which suggests genetic phenomena. 
To one who has read the data presented in the foregoing pages, certain 
similarities may be apparent between the Quercina in the Jimson Weed 
and rogues in peas investigated by Bateson and Pellew. 4 It will not be 
desirable, however, to discuss the two forms more in detail until grafting 
experiments with the rogues in peas have given definite results. 
A detailed account of the Quercina disease with photographs will appear 
shortly in the Journal of Genetics. 
1 Naudin, Ch., Nouvelles Recherches sur L'Hybridite dans les Vegetaux, Nouv. 
Arch. Mus., 1, 1865 (41-54). 
2 Godron, D. A., Des hybrides et des metis de Datura., Nancy, 1873 (1-75). 
3 Bateson, W. and Saunders, E. R-, Report to Evolution Committee of the Royal 
Society, 1, 1902 (21-32). 
4 Bateson, W. and Pellew, Caroline, "The Genetics of 'Rogues' among Culinary 
Peas," Proc. Royal Soc, 91, 1920 (186-195). 
