18 MARINE AND AQUATIC TRESPASSERS. 



refuse to believe that whales are not fish. " They 

 live in the water/' say they, " like fish, they feed like 

 fish, they die like fish when out of the water, and there- 

 fore fish they must be." 



Now let us proceed to sum up the details of 

 structure which enable these enormous mammals to 

 take possession of the seas, and so to trespass upon 

 the domains of the fish. 



The power of respiration is necessarily the first 

 requisite for a habitation in the water. Mammals, being 

 hot-blooded creatures, require a constant supply of 

 oxygenated blood, so that whales, being mammals, 

 must have this first necessity of existence. The 

 amount of blood which is poured through the system 

 of a whale is perfectly astonishing. I never appre- 

 ciated it until, while engaged in the Anatomical School 

 at Oxford, I assisted in preparing a section of an 

 aorta (i.e., principal artery of the heart) that had been 

 taken from a whale of moderate size. It looks some- 

 thing like a child's hoop, or a section of the main pipe 

 of some large waterworks. 



But I am quite sure that no one who was not 

 previously acquainted with the subject would ever 

 guess its real nature. Indeed, all those to whom I 

 have showed it have experienced some difficulty in 

 believing me, and have acknowledged that, without 

 having seen it, they never could have formed the least 

 conception of the gigantic proportions of the whale, 

 and of the vast torrent of blood that is driven through 

 its body. 



Three problems now present themselves. 



The first is this : The blood being there, how is a 



