78 EMBRYOLOGY IN ANTIQUITY [pt. ii 



University of Alexandria. That seat of learning, perhaps the most 

 glorious, after Athens, of any in antiquity, and greater than its con- 

 temporary rival Pergamos, was important because all the traditions 

 of earlier times were united in it like a bundle of strands coming 

 together to form a rope. Democritean atomism. Peripatetic science 

 and metaphysics, Goan biology, Coan and Cnidian medicine, above 

 all, Athenian mathematics and astronomy, all were gathered in 

 the fMovaelov of Alexandria under the benevolent dynasty of the 

 Ptolemies. The link between the Alexandrian biologists and the 

 school of Aristotle was Straton of Lampsacus, who, though apparently 

 not making any contribution to embryology himself, must have 

 brought the knowledge of generation gained by Aristotle to Alex- 

 andria as he sailed south across the Mediterranean to be the tutor 

 of Ptolemy Philadelphus. The link between Cos and Alexandria was 

 Diodes of Carystus, who was the last of the Hippocratic school and 

 also a pupil of Philistion of Locri. Diodes has a certain importance 

 in the history of embryology; for Oribasius refers to him as the dis- 

 coverer of the punctum saliens in the mammalian embryo, "on the 

 ninth day a few points of blood, on the eighteenth beating of the 

 heart, on the twenty-seventh traces of the spinal cord and head ". He 

 thus showed that the early development of chick and mammal was 

 very alike. Plutarch also tells us that he occupied himself with the 

 question of sterility. He described the human placenta, as well as 

 embryos of twenty-seven and forty days, and he held that both male 

 and female contribute seed in generation. Cnidian medicine in- 

 fluenced Alexandria through Chrysippus of Cnidus — not the Stoic — 

 whose embryological doctrine seems to have been that the embryo had 

 only a vegetative soul until birth or hatching. 



All these influences were fruitful, for they produced the two 

 greatest physiologists of ancient times, Herophilus of Chalcedon and 

 Erasistratus of Chios. These two, who were contemporaries during 

 the third century B.C., experimented much and wrote voluminously, 

 but all except fragments of their writings have been lost, and can 

 now only be pieced together out of the books of Galen, as has been 

 done by Dobson. Allbutt has well described the differences between 

 them, such as the predilection of Herophilus for the humoral patho- 

 logy and pharmacy, and the greater interest taken by Erasistratus in 

 atomistic speculations. "Herophilus", says Plutarch, "leaveth to 

 unbome babes a mooving naturall, but not a respiration, of which 



