DIVISIONS OF THE ANIMAL KINGDOM. Ixix 



together and produce a fruitful progeny, varieties of the 

 same species will breed together, and produce a fruitful pro- 

 geny. We shall be able, perhaps, in the sequel, to shew the 

 fallacy of this rule, as it is applied to many animals. It is 

 true that observation shews that animals which diverge from 

 one another beyond certain limits do not breed together, or, 

 breeding together, do not produce a fruitful progeny ; but it 

 is equally true, that animals may diverge from one another 

 beyond the limits of forms which we call specific, and yet 

 breed together. Many examples of this occur in the case of 

 the gallinaceous fowls which we rear in poultry-yards, and 

 of the little singing-birds brought up in cages ; and in the 

 case of fishes, experiments, from the facility of fecundifying 

 the sperm, are easily made to shew that not only animals 

 so divergent as species, so called, but as genera, may be 

 made to produce a fertile progeny. The Sheep and the Goat 

 breed together, and produce a progeny as fruitful as the pa- 

 rents ; yet the sheep and the goat are held to be distinct ge- 

 nera. They are distinct genera, indeed, according to our 

 classification, but it appears, from the effect, that they do 

 not diverge so much from one another in those characters 

 which enable animals to breed together, as to be incapable 

 of producing a common race ; and so it will be seen, in the 

 sequel, it is with other animals reduced to the state of do- 

 mestication. In the natural state, indeed, unions of this, 

 kind rarely take place, a provision having been apparently 

 made against their occurrence, in the habits and instincts of 

 the animals themselves. Species in the state of nature will 

 very rarely intermix ; and even varieties, produced by arti- 

 ficial breeding, tend to preserve themselves unmixed, when 

 in a state of liberty. If a flock of Merino Sheep, consisting 

 of rams and ewes, be mixed together in the same field with 

 a similar flock of the Heath Sheep of Scotland, there will be 

 na mixture between them, the females of each selecting the 

 rams of its own variety. In Wales, there are two vai^eties 

 of Sheep, one of which inhabits the higher mountains, and 



