What I have now said I have derived from numerous dissec- tions of human embryos of almost every size ; for I have had them for inspection from the time they were like tadpoles, till they were seven or eight fingers' breadth in length, and from thence onwards to the full time. I have examined them more particularly, however, through the second, third, and fourth months, in the course of which the greatest number of changes take place, and the order of development is seen with greatest clearness.
In the human embryo, then, of the age of two months, what we have spoken of as taking place in the " second process," is observed to occur. For I rather think that during the first month there is scarcely anything of the conception in the uterus at all events, I have never been able to discover any- thing. But the first month past, I have repeatedly seen concep- tions thrown off, and similar to the one which Hippocrates men- tions as having been voided by the female pipe-player, of the size of a pheasant's or pigeon's egg. Such conceptions resem- ble an egg without its shell ; they are, namely, of an oval figure; the thicker membrane or chorion with which they are sur- rounded, however, is seen to be covered with a white mucor externally, particularly towards the larger end ; internally it is smooth and shining, and is filled with limpid and sluggish water it contains nothing else.
In the course of the second month I have frequently seen an ovum of this description, or somewhat larger, thrown off with the symptoms of abortion, viz. ichorous lochia; the ovum being sometimes entire, at other times burst, and covered with bloody coagula. Within it was smooth and slippery ; it was covered with adhering blood without. Its form was that which I have just described. In some of these aborted ova, I have discovered embryos, in others I could find none. The embryo, when present, was of the length of the little finger-nail, and in shape like a little frog, save that the head was exceedingly large and the extremities very short, like a tadpole in the month of June, when it gets its extremities, loses its tail, and assumes the form of a frog. The whole substance was white, and so soft and mucilaginous, that unless immersed in clear water, it was impossible to handle it. The face was the same as that of the embryo of one of the lower animals the dog or cat, for
