SECT. 2] TO THE RENAISSANCE 103 



in contradistinction from Aristotle he makes the vegetative and 

 sensitive souls arrive automatically into the embryo but the rational 

 soul only by a direct act of God. 



His mammalian embryology presents some points of interest. He 

 follows Hippocrates ("Ypocras") in an account of the co-operation 

 of heat and cold in member-formation, and he holds very enlightened 

 views about foetal nutrition, "It appears therefore that the embryo 

 hangs from the cord and that the cord is joined with the vein and 

 that the vein extends through the uterus and has blood running 

 through it to the foetus like water through a canal. Round the embryo 

 there are membranes and webs as we have seen. But those who think 

 that the embryo is fed by little bits of flesh through the cord are 

 wrong and lie, because if this were the case with man it would happen 

 also with other animals and that it does not do so anybody can find 

 out by investigation [per anathomyani].'" 



Finally, it is typical that in Book xvii Albert repeats what he has 

 already said in Book vi about the generation of the hen out of the 

 tgg all over again with slight changes, but he adds the significant 

 biochemical remark that "eggs grow into embryos because their 

 wetness is like the wetness of yeast". The importance of Albert in 

 the history of embryology is clear. With him the new spirit of in- 

 vestigation leapt up into being, and, though there were many years 

 yet to pass before Harvey, the modern as opposed to the ancient 

 period of embryology had begun. Albert's writings were often 

 copied and printed in the next few centuries, and even as late as 1601 

 De Secretis Mulierum, an epitome of his books on generation, was 

 published. In some sense, it still is, as it forms the backbone of the 

 little book Aristotle's Masterpiece, of which thousands of copies are sold 

 in England every year. The copy of the De Secretis in the Caius College 

 Library has written across the title-page in faded ink "Simulacra 

 sanctitas, duplex iniquitas, Nathan Emgross, Nov. 20. 161 3." But in 

 spite of Mr Emgross, Albertus, rightly called Magnus, has had the 

 happy fate of being beatified both by the Church and by science. 



2-4. The Scholastic Period 



St Thomas Aquinas (i 227-1 274) incorporated the Aristotelian 

 theories of embryology into his Summa Theologica especially under 

 the head De propagatione hominis quantum ad corpus. There are some 

 striking passages, such as "The generative power of the female 



