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 a certain time, they continue barren. This is also the case with eggs, some of which, though they may have been conceived in consequence of intercourse, still remain unprolific unless per- fected by repeated and con tinned connections. Whence it happens that some eggs are more speedily changed by incubation than others, exhibiting traces of the foetus from the third day; others again, either become spoiled, or suffer transformation into the foetus more slowly, exhibiting no indications of the future chick even up to the seventh day, as shall be made to appear by and by, in speaking of the generation of the chick from the egg.

Thus far have we discoursed of the uterus of the fowl, and its function ; of the production of the hen's egg, and of its dif- ferences and peculiarities, from immediate observation; and from the instances quoted, conclusions may be drawn with reference to other oviparous animals.

We have now to pursue the history of the generation and formation of the foetus from the egg. For indeed, as I have said above, the entire contemplation of the family of birds is comprehended in these two propositions : how is an egg engen- dered of a male and female ; and by what process do males and females proceed from eggs ? the circle by which, under favour of nature, their kinds are continued to eternity.

EXERCISE THE FOUBTEENTH.

Of the production of the chick from the egg of the hen.

Of the growth and generation of the hen's egg enough has already been said; and we have now to lay before the reader our observations on the procreation of the chick from the egg, a duty which is equally difficult, and profitable, and pleasant. For in general the first processes of nature lie hid, as it were, in the depths of night, and by reason of their subtlety escape the keenest reason no less than the most piercing eye.

Nor in truth is it a much less arduous business to investigate the intimate mysteries and obscure beginnings of generation than to seek to discover the frame of the world at large, and the manner of its creation. The eternity of things is connected

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