111. THE HISTORY OF BIOLOGY 



organ for the blood and the veins emanating therefrom. Nor indeed was it 

 his object to gain any knowledge of the structure of the human body for any 

 biological or medical purpose; just as his method was speculative, so his 

 purpose was exclusively mystical-theological and he thus was content with 

 the old tradition as it stood, except in that one point in which it was not 

 consistent with his metaphysical construction of thought. However, he is 

 undoubtedly the first to expound a theory of the pulmonary circulation 

 agreeing with that confirmed by the research of later times. 



It is hardly to be supposed that a treatise which was prohibited by con- 

 temporary and later governments, and to the best of their powers suppressed, 

 would succeed in exercising any great influence on the progress of science; 

 it was, in fact, to be more than a century and a half before anyone drew atten- 

 tion to Servet's contribution to the discussion of the circulatory system. 

 Nevertheless, it would appear that Servet's ideas did after all have some 

 influence on his contemporaries, since during the latter half of the sixteenth 

 century one comes across in many authors statements, or at any rate hints, as 

 to the blood-circulation between the right and left ventricles through the 

 lungs. One or two of these writers, who had some influence on the final solu- 

 tion of the problem of the movement of the blood, should be mentioned here. 



Realdo Columbus, Vesalius's pupil and immediate successor in the chair 

 of anatomy in Padua, to whom we have referred above, may claim to be 

 named among the forerunners in this field, as he is the only author cited by 

 Harvey, the great pioneer of research work on the blood. Columbus in his 

 work on anatomy devotes a chapter to the vascular system. Here he presents 

 the traditional theory of the liver as the centre of the venous system and the 

 true blood-forming organ, from which the blood is conveyed to the diff^erent 

 parts of the body. The arterial system originates in the heart. Its right and 

 left ventricles are separated by an intermediate wall, which, contrary to the 

 common assumption, is impenetrable; from the right side the blood is con- 

 veyed to the lungs, where it is mixed with air and, thus diluted, is conducted 

 back to the right side of the heart. This, he adds, no one has hitherto ob- 

 served or described, but it is none the less true and can be verified on experi- 

 mental subjects, whether alive or dead. Columbus's work was published in 

 1559 — that is, six years after Servet's. There have been lively discussions 

 whether both arrived at the same conclusion independently, and, if not, of 

 which borrowed from the other. The question can of course never be defi- 

 nitely decided, but it is probable that Servet, who indisputably has the prior 

 claim on the point, in some way influenced Columbus; the latter presumably 

 read the dangerous heretical treatise, which he dared not quote even if he 

 had desired to do so. There is no doubt, however, that Columbus, in a far 

 greater degree than Servet, confirmed his statement by observation and 

 experiment. 



