iv] of Glands and Tissues. 95 



by laws different from those which determined the uses of 

 machines ; and thus there came to him the new conception of 

 an animal morphology. And his views broadened as, while 

 still regarding the study of man's structure as his first duty, he 

 pushed his researches into the structure of many animals, 

 vertebrate and invertebrate, and also of plants. All these' 

 studies more and more revealed to him general plans of struc- 

 ture and common laws of growth. As Harvey had been led to 

 new views by studying the uses of animal organs viewed as 

 machines, as Borelli had been led to other new views by 

 regarding the phenomena of the animal body as subject to 

 ordinary physical laws, so Malpighi was led to still other new 

 views by this new thought that the material of the living body 

 was subject to, and so its functions determined by, laws of 

 structure proper to itself, laws which we now call morphological. 



The first work which he published was that ' On the Lungs' 

 (De pulmonibus observation.es anatomicae) in 1661, in the form 

 of two letters to his friend and master Borelli, describing the 

 results of an inquiry which he carried out at Bologna im- 

 mediately after his return from Pisa. Up to that time little 

 or nothing was known of the real structure of the lung. It 

 was spoken of as fleshy, and its substance, which Fabricius had 

 compared to tow, was held to be a porous parenchyma, in which 

 the minuter divisions of the blood vessels on the one hand and 

 of the windpipe on the other were lost. It was into the spaces 

 of this porous fleshy parenchyma, as we have said, that the 

 blood of the pulmonary artery was supposed to be poured, 

 thence to be gathered up by the beginnings of the pulmonary 

 veins. 



In these brief epistles Malpighi announced two discoveries 

 of fundamental importance. In the first letter he described 

 the vesicular nature of the lung and shewed how the divisions 

 of the windpipe ended in the dilated air vesicles. He thus 

 for the first time supplied an anatomical basis for the true 

 conception of the respiratory process. 



In the same epistle he describes the network of blood 

 vessels, of arteries and veins (it may be worthy of note that 

 Malpighi always speaks of the pulmonary artery and pulmonary 



