120 FROM GALEN TO THE RENAISSANCE [pt. ii 



The obstetrical literature intended for midwives is also of great 

 interest. It was about this time that the first popular guides to their 

 subject began to appear, founded not upon mere superstition and 

 the remnants of ancient knowledge derived in roundabout fashion 

 through Syriac and Arabic, but either upon a careful study of Galen 

 and Aristotle, or upon the results of dissections and living speculation. 

 The principal representative of the former class is that of Jacob 

 Rueff, which appeared in 1554 and was called De Conceptu et Genera- 

 tione Hominis. Although written in Latin, it was evidently a popular 

 work, for the illustrations given in it are such as would naturally 

 be incorporated in such a book. It is the illustrations which give it 

 its importance, and I reproduce them in Fig. 6. I think they show 

 very clearly what the general ideas were at this period about mam- 

 malian embryology, and thus afford us a precious insight into what 

 was in the minds of such writers as Riolanus the elder, Mercurialis, 

 Saxonia, Rondeletius, Venusti, Holler and Vallesius. There are many 

 points which their expositions of foetal growth and development leave 

 vague, and without Rueff it would be difficult or impossible to picture 

 in what manner they imagined it to go on. Rueff 's text follows Galen 

 and Aristotle with fidelity, as does theirs — with the exception of a few 

 minor ideas not quite consonant with this. 



In (a) of Fig. 6 Rueff portrays the mixture of semen and menstrual 

 blood in the womb, or, as he loosely refers to it, of both seeds, 

 coagulating into a pink egg-shaped mass surrounded with a fine 

 pellicle, {b) shows the same mass in the uterus and wrapped round 

 with the three coats, amnion, chorion, and allantois — a lamentable 

 but interesting misrepresentation of the facts. Then in {c) it is shown 

 that upon the surface of the yolk-like mass of semen and blood 

 appear "three tiny white points not unlike coagulated milk", these 

 being the first origins of the liver, the heart, and the brain. Next {d) 

 shows the first blood-vessels springing from the heart, four in number, 

 and distributing themselves over the surface of the mass. It is plain 

 that Rueff must either have opened hen's eggs himself and seen the 

 early growth of the blastoderm or have been told about it by some 

 observer such as Goiter or Aldrovandus. He could not have copied 

 his pseudo-blastoderm pictures from their works, for in 1554 none 

 of them had appeared, and, as far as I know, there were no similar 

 illustrations in existence at that time. 



After this point the pictures grow even more fanciful, and, in (^), 



