SECTION 3 



EMBRYOLOGY IN THE SEVENTEENTH 

 AND EIGHTEENTH CENTURIES 



3-1. The Opening Years of the Seventeenth Century 



iEmilius Parisanus, a Venetian, now dealt with embryology in the 

 fourth, fifth, and sixth books of his De Subtilitate. They were entitled 

 as follows: "(4) Of the principles and first instruments of the soul 

 and of innate heat, (5) Of the material of the embryo and of its 

 efficient cause, (6) Of the part of the animal body which is first 

 made, and of the mode and order of procreation". Parisanus is 

 very wordy, but he has the merit of giving many quotations from 

 the lesser known authors, and providing (as a rule) accurate refer- 

 ences. He held that the spleen was formed in all development before 

 the heart, and that neither heart nor lungs moved in utero. With 

 regard to the controversy over the function of white and yolk, he 

 was in agreement with Fabricius, but he firmly opposed the view 

 that the chalazae were the first material of the chick, as much, it 

 must be confessed, because of the opinion of Aristotle as from his 

 own observation. Nevertheless, his own observations were note- 

 worthy, and he will always be remembered for his discovery of the 

 fact that the heart of the chick begins to beat some time before any 

 red blood appears in it. 



Parisanus was the last of the macro-iconographic group of sixteenth- 

 century embryologists. Their labours established the fundamental 

 morphological facts about the developing embryo; the first great 

 step in the history of embryology. But there were numerous errors 

 in their work, and Harvey, who occupies a terminal or boundary 

 position, was destined to correct them. He marks the transition from 

 the static to the dynamic conception of embryology, from the study 

 of the embryo as a changing succession of shapes, to the study of it 

 as a causally governed organisation of an initial physical complexity, 

 in a word, from Goiter and Fabricius to Descartes and Mayow. 

 Iconography did not die : on the contrary, the improvement of the 

 microscope gave it new life, and the micro-iconographic school 

 emerged with its principal glory, Malpighi. 



