SECT. 3] AND EIGHTEENTH CENTURIES 159 



But in the history of embryology these men and their writings have 

 a very great significance. Impressed by the unity of the world of 

 phenomena, they wished to derive embryology as well as physics 

 from fundamental laws. This attempt, which resulted in a Galen- 

 Epicurus synthesis on the one hand and a Galen-Descartes synthesis 

 on the other, must be regarded as a noble failure. Its authors did not 

 realise what a vast array of facts would have to be discovered before 

 a mechanical theory could with any justice be applied to explain 

 them. Gassendi and Descartes were like the Ionian nature-philo- 

 sophers, propounding general laws before the particular instances 

 were accurately known. Their ineffectiveness arises from the fact 

 that they did not themselves appreciate this, and consequently 

 worked out their idea in a prolix detail, the whole of which was 

 inevitably doomed to the scrap-heap from the very beginning. But 

 the spark was not to die ; and if anywhere in this history we are to 

 find the roots of physico-chemical embryology, we must pause to 

 recognise them here. 



Much less well known, but not without interest, was the Dissertatio 

 de vita foetus in utero of Gregorius Nymmanus, which appeared in the 

 same year as the second edition of Descartes' book, 1664. Nymmanus 

 writes with a very beautiful Latin style, and expresses himself with 

 great clearness. His proposition is, he says, "That the foetus in the 

 uterus lives with a life of its own evincing its own vital actions, and 

 if the mother dies, it not uncommonly survives for a certain period, 

 so that it can sometimes be taken alive from the dead body of its 

 mother". In supporting this thesis, Nymmanus answers the argu- 

 ments of those who had held that the lungs and heart of the foetus 

 were inactive in utero. Fabricius, Riolanus and Spigelius all proved, 

 says Nymmanus, that the mother and the foetus by no means neces- 

 sarily die at the same time. "The essential life", he says, "is the soul 

 itself informing and activating the body, the accidental life is the acts 

 of the soul which it performs in and with the body." Though the 

 foetus cannot be said to have life in the latter sense, it can in the 

 former. The foetus, says Nymmanus, prepares its own vital spirits 

 and the instruments of its own soul; there is no nerve between it and 

 its mother. If, he says, the foetal arteries got their sphygmic power 

 from the maternal heart, they would stop pulsating when the umbilical 

 cord was tied, but this is not the case. The pulse of the embryo is 

 therefore due to the foetal heart itself. Galen, says Nymmanus, was 



