114 EMBRYOLOGY FROM GALEN [pt. ii 



Aristotle or Aldrovandus had been able to bring to the matter. 

 On the third day, he saw the globulus sanguineus which in vitello 

 manifeste pulsabat, and so solved his first problem. He decides that 

 the first organ to be formed is the heart, and quotes Lactantius' 

 experiments. He explains the large size of the eye as due to the fact 

 that the most complicated part of the body needs the longest time 

 for its manufacture. He correctly describes the various membranes, 

 and the faeces subviridies in the intestines at hatching. Once he 

 contradicts Aristotle, maintaining that on the tenth day the body as 

 a whole is larger than the head, and once he contradicts Albertus, 

 denying that any yolk can be found in the stomach at hatching. He 

 concludes his tractate by a succinct and clear account of the opinions 

 of Aristotle and Hippocrates about embryonic development. His 

 importance is that he drew the attention of scientific thinkers to the 

 problems arising out of the hen's egg, and assisted in the formation 

 of that iconographic phase in embryology which was later to find 

 its climax in the plates of Fabricius, and its close in Harvey's Exer- 

 citations. 



Gabriel Fallopius, who belongs to this time, must be mentioned 

 as the discoverer of the organs which bear his name, but his services 

 to embryology were only indirect. A. Benedictus, who was now 

 growing old, and Caesar Cremonius, who was still young, may be 

 remembered as the principal upholders of pure Aristotelianism at this 

 time. Realdus Columbus also wrote on the embryo. B. Telesius, 

 in his De Natura Rerum of 1565, studied the hen's egg and suggested 

 that the parts of animals were formed by the pressure of the uterus 

 acting as a mould: he was thus the middle term between Galen 

 and Buffon. 



Julius Caesar Arantius has already been referred to. His De 

 Humano Foetu was an important book, but, though it appeared in 

 1564, just at the time when the macro-iconographic school was at 

 its height, it dealt with a rather different field and cannot be con- 

 sidered as a constituent of that group. He begins by relating that a 

 pregnant woman was killed by an accident at Bologna a couple of 

 years before, so that he had an opportunity of testing whether the 

 opinions about certain points in generation, which he had formed 

 on a priori grounds during the previous fifteen years, were true or 

 not. In the first place, he found on dissection that the placenta was 

 not cotyledonous, and he spoke thus of its formation: "Blood flows 



