ii6 EMBRYOLOGY FROM GALEN [pt. ii 



the yolk of the hen's egg is more earthy than the white, and looking 

 at it from all possible angles. He disagrees at last with Aristotle 

 and decides that the white is the more earthy. Bones, he says, are 

 white, but also very earthy. The albumen is colder, stickier, and 

 heavier than the yolk, "sequitur, terrestrius esse^\ And this particular 

 example is the more flagrant because the actual matter of it is 

 fundamentally physico-chemical. But, in addition, he introduced a 

 number of grave errors and misleading theories into embryology, so 

 that subsequently Harvey had to spend a large part of his time 

 refuting them. Fabricius was, indeed, a good comparative anatomist, 

 and it is upon that ground that he deserves praise: his plates, some 

 of which are reproduced herewith, were far better than anything 

 before and for a long time afterwards. He dissected embryos of man, 

 rabbit, guinea-pig, mouse, dog, cat, sheep, pig, horse, ox, goat, deer, 

 dogfish, and viper, a comparative study which had certainly never 

 been made previously. 



In his first tractate he begins by dealing with a question not unlike 

 that of how the sardines got into the tin, i.e. how the contents got 

 into the hard-shelled egg. He rejects Aristotle's idea that the egg 

 is formed in the oviduct by a kind of umbilicus, and ascribes its 

 growth there to transudation through the blood-vessels. He marks 

 a definite advance upon Aristotle when he says that silkworms and 

 other insects are born into their larval state from an egg, though he 

 still terms the chrysalis an egg, and therefore holds that they are 

 generated twice. Then follows his discussion of what part of the egg 

 the chick comes from. The chalazae, he says, are not semen, for the 

 semen is not present at all in the fertilised egg. His argument sounds 

 peculiar when he says that both the white and yolk of the egg are 

 the food of the embryo, for neither of them is absent at the end of 

 incubation, therefore neither of them is its material. Hippocrates 

 had said, "^ex luteo gigni, ex albo nutriri''; Aristotle had said, "ex 

 albo fieri, ex luteo nutrirV\ The latter was the view generally held 

 in the sixteenth century, as may be gathered from Ambrosius 

 Calepinus' dictionary, Scaliger's Commentary on Aristotle, and the 

 treatise on the soul of Johannes Grammaticus. 



Fabricius now says both nourish, neither makes. This distinction 

 between food and building-materials seems to us unnecessary, but 

 it had a great influence on later thought. Fabricius devotes much 

 time to proving, as he thinks, that albumen and white are of the 



