i8o EMBRYOLOGY IN THE SEVENTEENTH [pt. ii 



During this period also there were continued disputes about the 

 origin of the amniotic liquid, van Diemerbroeck and Verheyen con- 

 sidered that it could not be the sweat of the embryo, for the embryo 

 was always much too small to account for it, and, moreover, Tertre 

 had described cases where the secundines had been formed with the 

 membranes but in the absence of the embryo. Dionis affirmed that, 

 whatever it was, it could not be urine, for urine will not keep good 

 for nine days, a fortiori not for nine months. Drelincurtius put 

 forward a theory that the embryo secreted it from its eyes and mouth 

 by crying and salivating, while Bohn and Blancard derived it from 

 the foetal breasts. Lang, Berger and Gofey criticised this notion 

 without bringing forward anything constructive, and Gofey was in 

 his turn annihilated by D. Hoffmann, who with Nenter and Konig 

 supported the modern view, namely, that it was a transudation from 

 the maternal blood-vessels in the decidua. The question was com- 

 plicated further by the alleged discovery by Bidloo in 1 685 of glands 

 in the umbilical cord, and by Vieussens in 1 705 of glands on the 

 amniotic membrane. J. M. Hoffmann and Nicholas Hoboken sup- 

 ported the view that these were the important structures. There the 

 problem was left during the eighteenth century, various writers 

 supporting different opinions from time to time, and it is still under 

 discussion (see Section 22). 



Very early in the eighteenth century (1708) there appeared a 

 work by G. E. Stahl, van Helmont's most famous follower, which 

 struck the keynote of the whole century. Stahl's Theoria Medica Vera, 

 divided as it was into Physiological and Pathological sections, be- 

 longed in essence to the a priori school of Descartes and Gassendi. 

 It differed from them profoundly, of course, for, instead of trying to 

 explain all biological phenomena, including embryonic develop- 

 ment, from mechanical first principles, it started out from first 

 principles of a vitalistic order, and, having combined all the archaei 

 into one informing soul, it sought to show how the facts could 

 be perfectly well explained on this basis. But the spiritual kinship 

 of Stahl with Descartes and Gassendi is due to an atmosphere 

 which can only be called doctrinaire, and which was common 

 to them all. Like the methodist school of Hellenistic medicine, 

 they subordinated the data to a preconceived theory, during which 

 process any awkward facts were liable to be rather submerged than 

 subordinated. 



