lOO EMBRYOLOGY FROM GALEN [pt. ii 



is inclined to think that astrological influences may have an effect 

 on foetal life, but he treats the suggestion with considerable scepticism, 

 although he believes that thunder and lightning kill the embryos of 

 fowls (a popular belief to which Fere tried not long ago to give a 

 scientific foundation), and he regards the embryo of the crow as 

 especially susceptible, though on what grounds he does not say. 



The fourth chapter of the first tractate of the sixth book contains 

 Albert's description of development of the chick, and is extremely 

 interesting. He makes two principal mistakes: {a) he describes a 

 quite non-existent fissure in the shell by which the chick may emerge, 

 {b) he maintains that the yolk ascends after a day or two into the 

 sharp end of the egg, adducing as the reason that there is found 

 there more heat and formative force than elsewhere. On the other 

 hand, he correctly describes {a) the pulsating drop of blood on the 

 third day, and {b) he identifies it with the heart with its systolen et 

 dyastolen sending out the "formative virtue" to all the parts of the 

 growing body. He notices [c) that the differentiation of the chick at 

 first proceeds rapidly and later more slowly. But the most notable 

 characteristic of Albert's embryology is the way in which he is 

 hampered by his inability to invent a technical terminology. Singer 

 has studied the way in which anatomical terms, such as "syrach", 

 etc., came into use, but whatever the causes were which produced 

 them, they did not operate much in Albert's mind. He represents 

 the point beyond which embryology could not advance, until it 

 had created a new set of terms. This is well illustrated by the 

 following passage: 



"But fi'cni the drop of blood", he says, "out of which the heart is 

 formed, there proceed two vein-like and pulsatile passages and there is in 

 them a purer blood which forms the chief organs such as the liver and 

 lungs and these though very small at first grow and extend at last to the 

 outer membranes which hold the whole material of the egg together. There 

 they ramify in many divisions, but the greater of them appears on the 

 membrane which holds the white of the egg within it [the allantois]. The 

 albumen, at first quite white, is changed owing to the power of the vein 

 almost to a pale yellow-green tint [palearem colorem]. Then the path of 

 which we spoke proceeds to a place in which the head of the embryo is 

 found carrying thither the virtue and purer material from which are 

 formed the head and the brain, which is the marrow of the head. In 

 the formation of the head also are found the eyes and because they are of 

 an aqueous humidity which is with difficulty used up by the first heat 

 they are very large, swelling out and bulging from the chick's head. A short 



