ii6 PLANT HYBRIDIZATION BEFORE MENDEL 



"Altogether, I am at present disposed to regard King Red Chaff White 

 as perhaps one of the best wheats I have sowed." {ib., p. 3.) 



Shirreff also crossed Talavera, which has white chaff, with a 

 variety with small white seeds and red chaff. In this hybrid he 

 makes perhaps the first reference to color dominance in the chaff 

 of wheat. 



"The plant from the seed, in form of ear and seed, closely resembled 

 Talavera, but the color of the chaff was red." (ib., p. 33.) 



The dominance of downy chaff over smooth chaff, was also 

 recorded as follows : 



"A downy-chaffed variety with tall straw, which had been selected 

 from Hopetoun, was fecundated with pollen from Talavera, and the re- 

 sult was a constant variety with the downy chaff and fine straw of the 

 seed parent." (ib., p. 33.) 



Shirreff records (pp. 34-5) his observations on the natural 

 crossing of wheat in the field. 



"Having satisfied myself of the possibility of changing the seeds and 

 external characteristics of the wheat plant by crossing, I resolved to 

 attempt altering the habit of ripening." {ib., p. 36.) 



For this purpose he used a spring wheat known as Tuscany, 

 brought originally from New Zealand. Tuscany wheat was found 

 to ripen eight or ten days earlier than other kinds grown by him. 

 In 1869, he crossed Tuscany with King Richard and with Tala- 

 vera, with the object of improving the straw and grain of the 

 former variety, but of introducing its earlier ripening. From the 

 cross with King Richard he obtained earlier seeds, which were 

 planted in thumb pots. These were taken to the field, and six 

 plants finally came to harvest. The cross from Tuscany with 

 Talavera produced one plant. In 1811, these first-generation 

 hybrids were harvested. Shirreff, of course, assumed that the new 

 types thus appearing were as likely to be fixed in type as the 

 parents. 



Shirreff records, that of the seven first-generation hybrids, five 

 were summer and two winter wheat. Out of over eighty wheat 

 plants resulting from hybridization, he reports that he grew, in 

 1872, upwards of forty. 



As to the seldom occurrence of natural crossing, Shirreff notes : 



"if varieties growing contiguous are always instrumental in fecunda- 

 ing one another, my experimental plots must have long since become a 



