420 ON GENERATION. 



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 



