110 Malpighi and the Physiology [lect. 



about constriction of the veins, since this by opposing the flow 

 of blood would throw more material into the beginnings of the 

 duct. 



He is very clear as to the essential difference in nature 

 between the conglomerate (secreting) glands provided with 

 ducts and the conglobate (lymphatic) ductless glands, and 

 points out that lymph flows only from the former, whereas 

 it flows to and through the latter on its way to the venous 

 system. 



In yet another organ another discovery, an important aid to 

 the doctrine of secretion, was made about this time. 



In the year 1662 a pupil of Borelli's, one Laurentio Bellini, 

 a Florentine of good family, whether or no related to the great 

 Venetian painters I cannot tell, published a little tract De 

 structura renimi. He was then a mere youth of 19 years. 

 The Duke of Tuscany had sent to Borelli a deer to be used 

 for anatomical purposes, and Bellini, under Borelli's guidance, 

 carefully examined the kidneys. He then saw what no one 

 had seen before, that the substance of the kidney was composed 

 of minute tubules, urinary canaliculi, radiating from the pelvis 

 towards the surface. Eustachius had seen something of these, 

 but he described them as ' fuscous sulci ' ; it was Bellini who 

 really grasped their nature, and these straight tubuli uriniferi 

 (for he did not distinguish between the twisted and the straight 

 tubules) have since been known by his name. He described 

 the tubules as opening into the pelvis of the kidney, and guided 

 by the mind of his master Borelli expounded a physical theory 

 of the secretion of urine. The minute arteries, he says, 

 discharge their contents into spaces in the parenchyma of the 

 kidney, whence the aqueous serosity of the blood passes into 

 the beginnings of the urinary canaliculi, while the rest of the 

 blood finds its way out by the veins. The selection of the one 

 path and of the other is determined by the size and configura- 

 tion of the particles ; those of the aqueous serosity fit into the 

 canals of the canaliculi, those of the rest of the blood do not. 

 We see here a typical instance of the mechanical theories of 

 physiological events of which the master Borelli was so prolific. 



For a while Professor of Anatomy at Pisa, later on Bellini 



