PROSPECTIVE CONTRIVANCES. 173 



elaborately constructed for the alternate admission and ex- 

 pulsion of an elastic fluid, where no such fluid exists ; this 

 great organ, with the whole apparatus belonging to it, lies 

 collapsed in the foetal thorax ; yet in order, and in readiness 

 for action, the first moment that the occasion requires iU 

 service. This is having a machine locked up in store for 

 future use, which incontestably proves that the case was 

 expected to occur in which this use might be experienced ; 

 but expectation is the proper act of intelligence. Consider- 

 ing the state in which an animal exists before its birth, I 

 should look for nothing less in its body than a system of 

 lungs. It is like finding a pair of bellows in the bottom of 

 the sea ; of no sort of use in the situation in which they are 

 found ; formed for an action which was impossible to be ex- 

 erted ; holding no relation or fitness to the element which 

 surrounds them, but both to another element in another 

 place. 



As part and parcel of the same plan, ought to be men- 

 tioned, in speaking of the lungs, the provisionary contrivances 

 of the foramen ovale and ductus arteriosus. In the fojtus, 

 pipes are laid for the passage of the blood through the lungs ; 

 but until the lungs be inflated by the inspiration of air, that 

 passage is impervious, or in a great degree obstructed. What 

 then is to be done ? What would an artist, what would a 

 master do upon the occasion ? He would endeavor, most 

 probably, to provide a tc'niporary passage, which might carry 

 on the communication required, until the other was open. 

 Now this is the thing which is actually done in the heart. 

 Instead of the circuitous route through the lungs which the 

 blood afterwards takes before it gets from one auricle of the 

 heart to the other, a portion of the blood passes immediately 

 from the right auricle to the left, through a hole placed in the 

 partition which separates these cavities. This hole anat- 

 omists call the foramen ovale. There is likewise another 

 cross-cut, answering the same purpose, by what is called the 

 ductus arteriosus, lying between the pulmonary artery and 



