353 
We have now to consider the most important part of 
this question,—Are the offspring of hybrids continuously 
fertile ? 
“‘A hybrid plant,’ says M. Naudin, ‘is an individual in which are 
found blended, in an artificial union, two natures which are mutually 
opposed, and are continually striving to disengage themselves from 
one another.’ ”—(.Aftad P. Flourens. Examen du Livre de M. Darwin. 
A 97-) 
This assertion is a generalisation, based upon a certain 
amount of actual experience. It cannot be reasonably 
doubted that, when a hybrid race has been produced, 
it has often ceased to exist either through reversion to 
one of the parent forms or through inability to continuous 
fertility on the part of the race. And there need be no 
wonder that it is so! For we know that when members 
of the same species are submitted to new conditions, the 
effect is very varied on the constitution, especially with 
reference to the reproductive organs. Rut the question 
which we have now to consider is not whether the off 
spring of some hybrids are sometimes infertile or not 
continuously fertile, but whether the offspring of some 
hybrids are continuously fertile. The following evidence 
goes to show that the hybrid offspring of some species 
maintain at once their hybridity and their fertility. 
“A most attractive group of birds has just been placed by Pro 
fessor Flower in the great hall of the Natural History Museum, at 
South Kensington. The case is intended to illustrate the hybridisa 
tion of species in a state of nature, and the species selected are the 
hooded and carrion crows (Corvus cornix and C. corone) and the 
European and Asiatic goldfinches {Carduelis elegans and C.orientalis). 
The series of these birds has been presented to the Museum by 
Mr. Henry Seebohm, who procured the specimens himself during 
his travels in Siberia. The case of the crows is one of the few 
instances known of actual wild hybridisation, though many more are 
suspected, especially among the game birds. It is certain, however, 
that wherever the colonies of hooded crows meet the carrion crows 
W