the similarity of its consistency to that of the chalazse. But the red mass (which Fabricius regarded as the liver) is neither situated in nor near the chalaza, but in the middle of the clear colliquament ; and it is not any rudiment of the liver but of the heart alone. Neither does his view square with the example he quotes of the tadpole, " of which/' he says, " there is nothing to be seen but the head and the tail, that is to say, the head and spine, without a trace of upper or lower extremi- ties." And he adds, " he who has seen a chalaza, and this kind of conception, in so far as the body is concerned, will believe that in the former, he has already seen the latter." I, however, have frequently dissected the tadpole, and have found the belly of large size, and containing intestines and liver and heart pulsating ; I have also distinguished the head and the eyes. The part which Fabricius takes for the head, is the rounded mass [or entire body] of the tadpole, whence the creature is called ' gyrinus/ from its circular form. It has a tail with which it swims, but is without legs. About the epoch of the summer solstice, it loses the tail, when the ex- tremities begin to sprout. Nothing however occurs in the nature of a division of the embryo pullet into the head and spine, which should induce us to regard it as produced from the chalazse, and in the same manner as the tadpole.
The position and fame of Fabricius, however, a man exceed- ingly well skilled in anatomy, do not allow me to push this refutation farther. Nor indeed, is there any necessity so to do, seeing that the thing is so clearly exhibited in our history.
Our author concludes, by stating that his opinion is of great antiquity, and was in vogue even in the times of Aristotle.
For my own part, nevertheless, I regard the view of Ulysses Aldrovandus as the older, he maintaining, that the chalazse are the spermatic fluid of the cock, from which and through which alike the chick is engendered.
Neither notion, however, is founded on fact, but is the popular error of all times : the chalazse, treads, or treadles, as our English name implies, are still regarded by the country folks as the semen of the cock.
" The treadles (gran dines)," says Aldrovaudus; " are the spermatic fluid of the cock, because no fertile egg is without them." But neither is any unprolific egg without these parts,
