which at length emerge flies or butterflies of the several respects in which these differ in their mode of generation from an egg, from what we have found in the hen's egg, will be matter for remark in the proper place.
Although all eggs consisting of yelk and white are not pro- duced and fecundated in the same manner, but some are made prolific through the intercourse of male and female, and others in some other way (as of fishes) ; and although there is some difference even in the mode in which eggs grow, some attaining maturity within the body of the parent, others continuing to be nourished and to grow when extruded, there is still no reason why an embryo should not be developed in the same precise manner in every egg always understood as perfect as it is in the egg of the hen. Wherefore the his- tory which has been given of the evolution of the chick from the hen's egg may be regarded as applicable to the generation of all other oviparous animals whatsoever, as well as to the inferences or conclusions which may be deduced from thence.
EXERCISE THE SIXTY-THIRD.
Of the generation of viviparous animals.
Thus far have we treated mainly of the generation of ovi- parous animals ; we have still to speak particularly of the other species of generation, the viviparous, to wit, in which many things identical with those we have noticed in oviparous generation will come to be observed. These we have reduced into order, and here at length present for consideration. Even the parts that appear paradoxical and in contradiction with the current views of generation will, I believe, be found en- tirely in conformity with truth.
Among viviparous animals, man, the most perfect of all creatures, occupies the foremost place; after him come our ordi- nary domestic animals, of which some are soliped, such as the horse and ass ; others bisulcate, as the ox, goat, sheep, deer, and hog; others digitate, such as the dog, cat, rabbit, mouse, and others of the same description ; from the modes of whose
