ON GENERATION. 1/3 



denied that the feathered kinds have any diaphragm. The dif- 

 ficulty is resolved by admitting that birds are not entirely des- 

 titute of a kind of diaphragm, inasmuch as they have a delicate 

 membrane in the place of this septum, which Aristotle calls a 

 cincture and septum. Still they have no diaphragm that is 

 muscular, and that might aid respiration, like other animals. 

 But, indeed, Aristotle did not know the muscles/' 



Thus is the prince of philosophers accused and excused in 

 the same breath, his challenger being himself not free from 

 error; because it is certain that Aristotle both knew the mus- 

 cles, as I have elsewhere shown, and the membranes, which in 

 birds are not only situated transversely in the direction of the 

 cincture of the body, but extended in the line of the longitudi- 

 nal direction of the belly, supplying the place of the diaphragm 

 [of quadrupeds] and being subservient to respiration, as I have 

 shown in the clearest manner in my disquisitions on the Respi- 

 ration of Animals. And, passing over other particulars at this 

 time, I shall only direct attention to the fact, that birds breathe 

 with great freedom, and in singing also modulate their voice in 

 the most admirable manner, their lungs all the while being so 

 closely connected with their sides and ribs, that they can neither 

 be dilated and rise, nor suffer contraction in any considerable 

 degree. 



The bronchia or ends of the trachea in birds, moreover, are 

 perforate, and open into the abdomen (and this is an observa- 

 tion which I do not remember to have met with elsewhere), so 

 that the air inspired is received into and stored up within the 

 cells or cavities formed by the membranes mentioned above. 

 In the same manner as fishes and serpents draw air into ample 

 bladders situated in the abdomen, and there store it up, by 

 which they are thought to swim more lightly ; and as frogs and 

 toads, when in the height of summer they respire more vigo- 

 rously assume more than the usual quantity of air into their ve- 

 sicular lungs, (whence they acquire so large a size,) which they 

 afterwards freely expire, croaking all the while; so in the fea- 

 thered tribes are the lungs rather the route and passage for 

 respiration than its adequate instrument. 



Now, had Fabricius seen this, he would never have denied 

 that these membranes (with the assistance of the abdominal 

 muscles at all events,) could subserve respiration and perform 



