HYBRIDOUS ANIMALS. 420 
duals of a particular species are drawn together by mutuat 
sympathy, and excited to action by a common propen- 
sity. The produce of a conjunction between individuals 
of the same species, partakes of the characters common to 
the species, and exhibits in due time the characteristic 
marks of puberty and fertility. In a natural state, the se- 
lective atiribute of the procreative instinct unerrmgly guides 
the individuals of a species towards each other, and a pre- 
ventive aversion turns them with disgust from those of an- 
other kind. 
In a domesticated state, where numerous instincts are 
suppressed, and where others are fostered to excess, indivi- 
duals belonging to different species are sometimes known 
to lay aside their natural aversion, and unite in the busi- 
ness of propagation. Instances of this kind occur among 
quadrupeds, birds and_fishes,—among viviparous and ovi- 
parous animals,—where impregnation takes place within 
as well as when it 1s effected without the body. The pro- 
duct of such an unnatural union is termed-a Hybridous 
animal. The following circumstances appear to be con- 
uected with hybridous productions. 
1. The parents must belong to the same natural genus 
or fumily.—There are no exceptions to this law. Where 
the species differ greatly in manners and structure, no con; 
straint or habits of domestication will force the unnatural 
union. On the other hand, sexual union sometimes takes 

young plants, are prepared in the absence of sexual organs, and, consequent- 
ly, without impregnation. Upon falling off from the parent, they strike 
root and enjoy an individuality of character, as decided as if the reproduce 
tive organs had gone through the whole of the ordinary process. By means 
of such extensions, and without ever producing seeds, the Festuca vivipara 
is found in every pasture field of the northern islands of Scotland. When 
extensions are obtained from healthy parents, or generated by such, their 
duration will probably extend to the ordinary term assigned to the species. 
