He is also mistaken when he speaks of the chalaza, as pro- per parts of the egg. The egg consists in fact but of white and yelk ; the chalazse as well as the membranes, are mere appendages of the albumen and vitellus. The chalazse, in particular, are the extremities of certain membranes, twisted and knotted ; they are produced in the same way as a rope is formed by the contortion of its component filaments, and exist for the purpose of more certainly securing the several elements of the egg in their respective places.
Fabricius, therefore, reasons ill when he says, that " the chalazse are found in the part of the egg where the embryo is produced, wherefore it is engendered from them ;" for even on his own showing, this could never take place, he admitting that the chalazse are extant in either extremity of the egg, whilst the chick never makes its appearance save at the blunt end ; in which, moreover, at the first commencement of gene- ration, no chalaza can be seen. Farther, if you examine the matter in a fresh egg, you will find the superior chalaza not immediately under the blunt end or its cavity, but declined somewhat to the side; not to that side, however, where the cavity is extending, but rather to the opposite side. Still far- ther, from what has preceded, it is obvious that the relative positions of the fluids of the egg are altered immediately that incubation is begun : the eye increased by the colliquament is drawn up towards the cavity in the blunt end of the egg, whence the white and the chalaza are on either hand with- drawn to the side. For the macula or cicatricula which before incubation was situated midway between the two ends, now in- creased into the eye of the egg, adjoins the cavity in the blunt end, and whilst one of the chalazse is depressed from the blunt end, the other is raised from the sharp end, in the same way as the poles of a globe are situated when the axis is set ob- liquely ; the greater portion of the albumen, particularly that which is thicker, subsides at the same time, into the sharp end.
Neither is it correct to say, that the chalazse bear a resem- blance in length and configuration to the chick on its first formation, and that the number of their nodules corresponds with the number of the principal parts of the embryo; a statement which gives Fabricius an opportunity of adducing an argument connected with the matter of the chick, based on
