142 CANNON: STUDIES IN PLANT Hysrips 
The variations of the hybrids are many and complex, and it 
would be impossible as well as unnecessary for the purposes of 
this paper to attempt to present anything like a full account of the 
subject, much less to give a very complete list of hybrids to illus- 
trate the variations. What I shall give is largely drawn from the 
work of Focke already quoted, and a shorter one by Swingle and 
Webber,* although I shall not confine myself wholly to these 
sources. 
The characters of the parents may be perfectly blended in 
the hybrid so that neither parent is “ favored” (Datura Metel x 
D. meteloides, Geum intermedium +). In other cases the hybrid 
may not be intermediate but may exhibit all grades of the char- 
acters by which the parents are distinguished from each other 
(Aduti‘on hybrids), even reproducing in great detail either parent 
(Hieracium hybrids, those of the maize, Cytisus Adami{ and 
the pods of some hybrid peas, etc. §). Or the hybrid may 
show the characters of either parent without intermediate grades 
(strawberry hybrids). The foregoing refers to the behavior of 
the hybrids of the first generation, or those of the primary cross ; 
in the second generation the variations are equally well marked. 
In the second generation the hybrids that were intermediate 
and uniform in the first one may remain so (Geum intermedium, 
Burbank’s raspberry-dewberry hybrid). Or such hybrids may 
vary (Nicotiana rustica x N. paniculata). Hybrids which present 
variations in the first generation tend to become more variable in 
the second and third generations. Those that in the first genera- 
tion resembled either parent may continue to revert in a similar 
manner (strawberry hybrids), or an intermediate condition may be 
present in addition to the extreme racial forms (Datura Metel x D. 
metelotdes). 
Another phase of variation is found in the changes that a 
hybrid may exhibit in the course of its life, or ontogeny. In the 
earlier stages it may show the characters of one parent, and in 
* Swingle & Webber, Hybrids and their. ‘Udiigation. in ‘Plant Breeding. Yearb, 
U. S. Dep. Agric. 1897: 383. 1898. 
¢ Salter, On the Fertility of certain Hybrids. Phytologist, 4: 737. 1852. 
{ Farmer. Ann. Bot. 11: 538. 1897. 
; Tschermak, Weitere Beitrige iiber Verschiedenwerthigkeit der Merkmale bei 
Kreuzung von Erbsen und Bohnen, Ber. Deuts. Bot. Gesells. 19: 35. 1901. 
