128 EMBRYOLOGY IN THE SEVENTEENTH [pt. ii 



Riolanus the younger, the correspondent and almost exactly the 

 contemporary of Harvey, was Professor in Paris and published his 

 Anthropographia in 1618. As he was a keen advocate of the ancient 

 views, his section on the formation of the foetus has little importance. 

 Yet it contains the first known instance of the use of the lens in embryo- 

 logy, the germ of that powerful instrument which was to lead in 

 due course to so many discoveries. "In aborted embryos", said 

 Riolanus, "the structure is damaged and can often not be properly 

 seen, even when you make use of lenses [conspicilid] which make 

 objects so much bigger and more complicated than they ordinarily 

 seem." 



The De Formatrice Foetus of Thomas Fienus, Professor at Louvain 

 and a friend of Gassendi, published in 1620, is interesting because 

 it is the middle term between Aristotle and Driesch. As the title- 

 page informs us, he sets out to demonstrate that the rational soul is 

 infused into the human embryo on the third day after conception. 

 This by itself would not be very attractive, but the most cursory 

 inspection shows that Fienus' interests were not at all theological. 

 He divides the book up into seven main questions, (i) What is the 

 efficient cause of embryogeny? He concludes that it is neither God, 

 nor Intelligence, nor anima mundi (influence of Neo-platonism here 

 as on Galileo). (2) Is it in the uterus or in the seed? In the latter, 

 says Fienus, adding a list of authorities who agree with this view — 

 Haly-Abbas, Gaietanus, Zonzinas, Turisanus, Fernelius, Vallesius, 

 Peramatus, Saxonia, Carrerius, Zegarra, Mercurialis, Massaria, and 

 Archangelus, ^' solus Fabio Pacio utero imprudenter adscribit'' (!). (3) Is 

 it heat? Fienus nearly decided that it was, and, if he had done 

 so, would have shown a modern mind, but no, he gave his 

 opinion against it, saying, "the process (of development) is so divine 

 and wonderful that it would be ridiculous to ascribe it to heat, a 

 mere naked and simple quality". After weighing various other 

 alternatives in questions (4), (5) and (6), he asks whether it is 

 ^'^ anima seminis post conceptum adveniens'' (7), and concludes that it is. 

 It is here that he becomes really interesting, for he quotes with 

 approval certain writers, e.g. Alexander Aphrodisias [Organicum corpus 

 esse organicum ab anima et anima praeexistere organizationi) , Themistius 

 {Anima fabricatur architecturaque sibi domicilium et accommodatum instru- 

 mentum) and Marsilio Ficino in his commentary on Plato's Timaeus 

 [Priusquam adultum sit corpus, anima tota in illius fabrica occupatur), and 



