32 CIRCULATION OF THE BLOOD 



which is derived from the liver. Hence the spirit is said 

 to be in the blood, or to be blood. The spirit is not said 

 to be in the chambers of the heart, nor yet in the mass of 

 the brain or liver, but in the blood itself, as God Himself 

 teaches in Genesis, chap. ix. [ver. 4] ; Leviticus, chap, 

 xvii. [ver. n] ; and Deuteronomy, chap. xii. [ver. 23]." 



In all this there are only the doctrines of Galen and 

 Aristotle slightly altered by the theology of Servetus and 

 especially by his reading of the Bible. The one real 

 change that he has made is to do away with the natural 

 spirits, the product of the liver. He therefore admits 

 only one kind of spirits in the blood, whether arterial or 

 venous. This idea, it may be thought, would make it 

 necessary for him to emphasise the communications 

 between veins and arteries, because the vital spirit that 

 is formed in the heart, and especially in the left ventricle, 

 cannot get into the veins without such communication. 



Now there is a passage in the writings of Galen in 

 which he speaks of anastomosis between the arteries and 

 veins. In older Greek the word anastomosis meant the 

 act of making a mouth or hole. In later writings, how- 

 ever, the word came to mean something rather different. 

 It might be used for two structures that are closely 

 intertwined or connected with each other as are the veins 

 and arteries, and Galen sometimes uses the word in this 

 latter sense. In the passage in question, however, he 

 has certainly the original meaning, 1 and really seems 

 to imply that there are certain openings between the 

 arteries and the veins. He does not, however, attach 

 importance to these openings. They are not necessary 

 for his physiological system. Galen's actual phrase is 

 ' throughout the body the arteries anastomose with the 



1 De nsu partium, vi. 10. The actual word he uses here is 

 <TvvavaaT6/j.ioi>Ta.i, which undoubtedly means that the vessels are joined 

 together by a mouth. A similar statement is made in vi. 17. 



