Page:The Works of William Harvey (part 1 of 2).djvu/438

 In all there is the same transmutation or generation from the same to the same ; as concerns a part, this is performed by the process of nutrition and augmentation, but as regards the whole, by simple generation ; in other respects the same pro- cesses occur equally. For from the same source from which the material first takes its existence, from that source also does it gain nutriment and increase. Moreover, from what we shall presently say, it will be made clear that all the parts of the body are nourished by a common nutritious juice ; for, as all plants arise from one and the same common nutriment, (whe- ther it be dew or a moisture from the earth,) altered and con- cocted in a diversity of manners, by which they are also nourished and grow ', so likewise to identical fluids of the egg, namely, the albumen and the yelk, do the whole chick and each of its parts owe their birth and growth.

We will explain, also, what are the animals whose generation takes place by metamorphosis, and of what kind is the pre- existent material of insects which take their origin from a worm or a caterpillar ; a material from which, by transmutation alone, all their parts are simultaneously constituted and embodied, and a perfect animal is born ; likewise, to what animals any constant order in the successive generation of their parts attaches, as is the case with such as are at first born in an imperfect condition, and afterwards grow to maturity and per- fection ; and this happens to all those that are born from an egg. As in these the processes of growth and formation are carried on at the same time, and a separation and distinction of parts takes place in a regularly observed order, so in their case is there no immediate pre-existing material present, for the incorporation of the foetus, (such as the mixture of the semina of the male and female is generally thought to be, or the menstrual blood, or some very small portion of the egg,) but as soon as ever the material is created and prepared, so soon are growth and form commenced; the nutriment is immediately accompanied by the presence of that which it has to feed. And this kind of generation is the result of epigenesis as the man proceeds from the boy; the edifice of the body, to wit, is raised on the punctum saliens as a founda- tion; as a ship is made from a keel, and as a potter makes a vessel, as the carpenter forms a footstool out of a piece of