ANIMALS. 



129 



<luced many to assert, that all animals are pro- 

 duced from eggs, in the same manner. They 

 consider an egg excluded from the body by 

 some, and separated into the womb by others, 

 to be actions merely of one kind ; with this 

 only d inference, that the nourishment of the 

 one is kept within the body of the parent, and 

 increases as the embryo happens to want the 

 supply ; the nourishment of the other is pre- 

 pared all at once, and sent out with the be- 

 ginning animal, as entirely sufficient for its 

 future support. But leaving this to the dis- 

 cussion of anatomists, let us proceed rather 

 with facts than dissertations ; and as we have 

 seen the progress of an oviparous animal, or 

 one produced from the shell, let us likewise 

 trace that of a viviparous animal, which is 

 brought forth alive. In this investigation, 

 Graaf has, with a degree of patience charac- 

 teristic of his nation, attended the progress 

 and increase of various animals in the womb, 

 and minutely marked the changes they un- 

 dergo. Having dissected a rabbit, half an 

 hour after impregnation, he perceived the 

 horns of the womb, that go to embrace and 

 communicate with the ovary, to be more red 

 than before ; but no other change in the rest 

 of the parts. Having dissected another, six 

 hours after, he perceived the follicules, or the 

 membrane covering the eggs contained in the 

 ovary, to become reddish. In a rabbit dis- 

 sected after twenty-four hours, he perceived, 

 in one of the ovaries, three follicules, and, in 

 the other, five, that were changed ; being be- 

 come, from transparent, dark and reddish. 

 In one dissected after three days, he per- 

 ceived the horns of the womb very strictly to 

 embrace the ovaries ; and he observed three 

 of the follicules in one of them, much longer 

 and harder than before : pursuing his inqui- 

 sition, he also found two of the eggs actually 

 separated into the horns of the womb, and 

 each about the size of a grain of mustard-seed; 

 these little eggs were each of them inclosed 

 in a double membrane, the inner parts being 

 filled with a very limpid liquor. After four 

 days, he found, in one of the ovaries, four, and 

 in the other, five fbllicules, emptied of their 

 eggs: and in the horns correspondent to these, 

 he found an equal number of eggs thus sepa- 

 rated: these eggs were now grown larger than 

 before, and somewhat of the size of sparrow- 



shot. In five days, the eggs were grown to 

 the size of duck-shot, and could be blown 

 from the part of the womb where they were, 

 by the breath. In seven days, these eggs 

 were found of the size of a pistol-bullet, each 

 covered with its double membrane, and these 

 much more distinct than before. In nine days, 

 having examined the liquor contained in one 

 of these eggs, he found it, from a limpid colour, 

 less fluid, to have got a light cloud floating 

 upon it. In ten days, this cloud began to 

 thicken, and to form an oblong body, of the 

 figure of a little worm : and, in twelve days, 

 the figure of the embryo was distinctly to be 

 perceived, and even its parts came into view. 

 In the region of the breast he perceived two 

 bloody specks ; and two more, that appeared 

 whitish. Fourteen days after impregnation, 

 the head of the embryo was become large and 

 transparent, the eyes prominent, the mouth 

 open, and the rudiments of the ears begin- 

 ning to appear; the back-bone, of a whitish 

 colour, was bent towards the breast ; the two 

 bloody specks being now considerably increas- 

 ed, appeared to be nothing less than the out- 

 lines of the two ventricles of the heart; and 

 the two whitish specks on each side, now ap- 

 peared to be the rudiments of the lungs ; to- 

 wards the region of the belly, the liver began 

 to be seen, of a reddish colour: and a little 

 intricate mass, like ravelled thread, discerned, 

 which soon appeared to be the stomach and 

 the intestines : the legs soon after began to be 

 seen, and to assume their natural positions: 

 and from that time forth, all the parts being 

 formed, every day only served to deveJope 

 them still more, until the thirty-first day, when 

 the rabbit brought forth her young, complete- 

 ly fitted for the purposes of their humble 

 happiness. 



Having thus seen the stages of generation 

 in the meaner animals, let us take a view of its 

 progress in man ; and trace the feeble begin- 

 nings of our own existence. An account of 

 the lowliness of our own origin, if it cannot 

 amuse, will at least serve to humble us; and 

 it may take from our pride, though it fails to 

 gratify our curiosity. We cannot here trace 

 the variations of the beginning animal, as in 

 the former instances; for the opportunities 

 of inspection are but few and accidental : for 

 this reason, we must be content often to fill 



