AN ANATOMICAL STUDY ON THE 



impossible and unbelievable. They are of that class 

 of men, as I reply with the poet, who promptly agree 

 or disagree, according to their whim, fearful when 

 wanted, bold when there is no need. 



The substance of the liver and also of the kidney 

 is very dense, but that of the lung is much looser, and 

 in comparison with the liver and kidney is spongy.^ 



There is no propulsive force in the liver, but in the 

 lung the blood is pushed along by the beat of the 

 right ventricle of the heart, which must distend the 

 vessels and pores of the lung. Again, as Galen in- 

 dicates {De Usu Part.^ cap. jo), the continual rising 

 and falling of the lungs in respiration must open and 

 close the vessels and porosities, as in a sponge or 

 thing of similar structure when it is compressed and 

 allowed to expand.^ The liver, however, is quiet, 

 it never seems to expand or contract. 



2 This later developed into the question of an "open" or a "closed" 

 circulation through an organ. The microscopic structure of the in- 

 ternal organs, which gives the clue to their architecture and functional 

 mechanism, was first investigated by Marcello Malpighi (1628-1694), 

 the brilliant Italian scientist. In his De pulmonibus (1661) he gave 

 the first clear conception of the structure of the lung, and completed 

 Harvey's demonstration (announced the year of his birth) by proving 

 the capillary anastomoses between arteries and veins. In his De 

 yiscerum structura (1666) he outlined the structure of the liver, 

 spleen, and kidney. The best modern work on the architecture of 

 the kidney has been done by J. Henle (i 809-1 885), of the Hver by 



F. P. Mall (1862- 1917), and of the lung by W. S. Miller (1858 ). 



The question of an open versus a closed circulation through an organ 

 seems to be settled in favor of the latter. 



^ Respiration does considerably influence blood-pressure. It is 

 generally agreed that blood-pressure rises during inspiration and falls 

 during expiration. For a discussion of the factors involved, see: R. 



f62l 



