no EMBRYOLOGY FROM GALEN [pt. ii 



Necessity is Nature's master and guardian, it is Necessity that makes 

 the eternal laws". If Aristotle is the father of embryology regarded 

 as a branch of natural history, Leonardo is the father of embryology 

 regarded as an exact science. 



2-6. The Sixteenth Century: the Macro- Iconographers 



After such a man, the writings of his contemporaries, such as the 

 mythical Johannes de Ketham, Alessandro Achillini and Gabriele de 

 Gerbi, appear beyond description inferior. De Ketham's embryology 

 has been described by Ferckel. De Gerbi included in his Liber 

 Anatomiae corporis humani et singulorum membrorum illius a section 

 entitled De Generatione Embrjonis, but there is nothing to be said 

 about it except that it is a verbose compilation of the views of 

 Aristotle and Galen taken from Avicenna. The work of Nolanus in 

 1532 presents certain points of interest, but it is of little importance. 

 Petrus Crescentius in his work on husbandry of 1548 mentions 

 artificial incubation in ovens, but rather as a lost art. About this 

 time also Hieronymus Dandinus Cesenas, a Jesuit, wrote a treatise 

 on Galen's division of organs into white and red, those proceeding 

 from the semen and those proceeding from the blood: it is cited by 

 Aldrovandus, but I have not been able to consult it. 



The most remarkable feature of the first half of the century was 

 the encyclopaedic group of zoologists which now arose. Thus Belon 

 and Rondelet, whose well-illustrated catalogues of animals were 

 appearing from 1550 onwards, did a good service to comparative 

 embryology in figuring the ovoviviparous selachians and viviparous 

 cetacea. Gesner belongs to this group. All of them reproduce thin 

 versions of Aristotle, when they speak of generation as such, and this 

 is what differentiates them from Ulysses Aldrovandus, of whom I 

 shall speak presently. Figs. 3 and 4 show Rondelet's pictures of a 

 viviparous dolphin and an ovoviviparous selachian. 



But the end of the twilight period was now at hand, for, within 

 thirty years after the death of de Gerbi in 1505, four great 

 embryologists were born as well as the greatest anatomist of any age, 

 Andreas Vesalius (1514), of whom I shall say no more, for he had 

 no opportunities for dissecting human embryos, and took hardly 

 any interest in foetal development. But in 1522 Ulysses Aldrovandus 

 was born, and in the following year Gabriel Fallopius, in 1530 

 Julius Caesar Arantius and in 1534 Volcher Goiter. Only three 



