Page:The Works of William Harvey (part 1 of 2).djvu/314

 among housewives that the chalazse are the tread or spermatic fluid of the cock, and that the chick is generated from them is discovered to be a vulgar error. But Fabricius himself, al- though he denies that they consist of the semen of the cock, still gives various reasons for maintaining chat " they are the immediate matter which the cock fecundates, and from which the chick is produced ;" a notion which he seeks to prop by this feeble statement : " because in a boiled egg, the cha- lazse are so contracted on themselves that they present the figure of a chick already formed and hatched." But it is not likely that several rudiments of a single foetus should be wanted in one egg, neither has any one ever discovered the rudiments of the future chick save in the blunt end of the egg. More- over the chalazse present no sensible difference in eggs that are fecundated by the intercourse of the two sexes, from those of eggs that are barren. Our distinguished author is therefore mistaken in regard to the use of the chalazse in the egg, as shall farther be made to appear by and by.

In the eggs of even the smallest birds there is a slender fila- ment, the rudiments of the chalazse, to be discovered; and in those of the ostrich and cassowary I have found, in either end of the egg very thick chalazse, of great length, and very white colour, made up of several globules gradually diminishing in size.

A small cavity is observed in. the inside of an egg under the shell, at the blunt end ; sometimes exactly in the middle, at other times more to one side, almost exactly corresponding to the chalaza that lies below it. The figure of this cavity is generally circular, though in the goose and duck it is not exactly so. It is seen as a dark spot if you hold an egg opposite a candle in a dark place, and apply your hand edgeways over the blunt end. In the egg just laid it is of small size, about the size of the pupil of the human eye ; but it grows larger daily as the egg is older, and the air is warmer ; it is much increased after the first day of incubation ; as if by the exhalation of some of the more external and liquid albumen the remainder con- tracted, and left a larger cavity; for the cavity in question is produced between the shell and the membrane which surrounds the whole of the fluids of the egg. It is met with in all eggs ; I have discovered it, even in those that are still contained in the uterus, as soon as they had become invested with the shell.