50 Harvey and the [lect. 



clearly indeed that his newly discovered vessels were channels 

 for conveying the chyle, the elaborated contents of the in- 

 testine, away from the intestine; but influenced doubtless by 

 the accepted view that all the absorbed food must be carried to 

 the liver to be there elaborated into blood, he went wrong as 

 to the ultimate course taken by these vessels ; he could trace 

 them he thought into the liver. It may here be noted in 

 passing that Aselli in his treatise speaks of and indeed figures 

 the cluster of lymphatic glands lying in the mesentery as ' the 

 pancreas'; and this cluster of glands was afterwards often 

 spoken of as ' the pancreas of Aselli.' 



Aselli's discovery by itself was not perhaps of capital 

 importance ; and indeed for a quarter of a century it remained 

 an isolated and barren bit of knowledge. After that interval, 

 however, Jean Pecquet, a French physician who practised first 

 in Dieppe and subsequently in Paris, in his Experimenta 

 nova anatomica, published in Paris in 1651, made known 

 a further discovery, one which he says he had come upon years 

 before while studying at Montpellier, the discovery of the 

 receptacle of the chyle and its continuation as the thoracic 

 duct. Pecquet not only accurately describes these structures, 

 but shews that on the one hand Aselli's lacteals pour their 

 contents into the receptacle, and that on the other the thoracic 

 duct, the continuation of the receptacle, pours its contents into 

 the venous system at the junction of the jugular and sub- 

 clavian veins. In the following year, 1652, Van Horn made 

 known the same discovery, which he appears to have arrived at 

 quite independently of Pecquet. 



By this discovery of the thoracic duct and its entrance into 

 the veins, a wholly new aspect was given to Aselli's original 

 observation. The mere existence of special vessels such as the 

 lacteals in the mesentery was quite consistent with, indeed 

 supported, the old views of the circulation. Pecquet's observa- 

 tion was wholly inconsistent with them ; but between Aselli 

 and Pecquet, Harvey's book had appeared ; and it may be 

 taken as a proof of how profoundly Harvey's arguments had 

 in so short a time influenced men's minds, that Pecquet's 

 observations, which if put forward thirty years before would 



