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C E T A C E A. 



plunges to a great depth. In such cases, the water has 

 of course access to the upper reservoirs, from which 

 the water is expelled in blowing ; but the valves at 

 the lower part of these are closed the more firmly, 

 the greater the pressure of the water ; that is, the 

 greater the depth to which the animal plunges. 

 Hence a whale always blows when it comes to the 

 surface after a plunge. 



There is no inconsiderable resemblance between 

 the stomach of the cctacea, and that of ruminating 

 animals ; and this holds in most varieties of the 

 cetacea, whatever may be the nature of their food. 

 It consists of four or five distinct cavities, the con- 

 nexions between which are very like those in the 

 ruminants. But there is this difference between 

 them, that, in the cetacea there is no rumination, or 

 even approach to it ; the food once taken into the 

 stomach does not again return to the mouth ; and 

 indeed there is not, even in those which have teeth 

 in both jaws, any apparatus by which the food could 

 be further prepared for digestion, than it is by simple 

 capture at the first. 



In the porpoises and dolphins, the species with 

 which we are best acquainted, and have the best 

 means of examining, as they are plentiful on many 

 parts of the coast, indeed on all parts of it, at some 

 seasons ; in them the first stomach is the largest, and 

 it is of an oval form, having thick convolutions on its 

 central surface, and elevated ridges round the opening, 

 by which it communicates with the second one. At 

 the end of this first stomach, and connecting it with 

 the second one, there is a short canal. The second 

 stomach is oval as well as the first, but it is of smaller 

 dimensions, and has its sides with rounded longitu- 

 dinal and transverse ridges ; and this one also com- 

 municates by a short canal with the third. The third 

 is of much less diameter in proportion to its length 

 than the others, and has a contrary llexure which 

 gives it something the figure of the letter S laid flat. 

 This portion bears some resemblance to a wide intes- 

 tine, and its walls have their furrows and ridges much 

 finer than those of the first and second. Indeed this 

 one is generally almost smooth in its walls, and also 

 soft and pliant in texture. The outlet of this third 

 stomach has a coat or valvular shutter, composed of 

 three membranes. The fourth stomach is rather 

 round in its form, and much smaller than any of the 

 others. It is nearly of the same structure and con- 

 sistency with the third stomach. 



The intestinal canal is usually very long, with 

 many folds of the central membrane, which appears 

 to serve as valves in propelling, or at all events pre- 

 venting the return of the contents of this long and 

 tortuous canal. This intestine becomes very small 

 in diameter towards the final opening. 



The food of the cetacea, notwithstanding the great 

 similarity there is in their digestive apparatus, varies 

 considerably in consequence of the differences in their 

 teeth and capacity of swallowing. The Sa/ccua and 

 narwhals subsist chiefly upon floating mollusca and 

 radiata, though they also swallow great numbers of 

 small fishes, especially herrings, one of which is about 

 the largest morsel which can enter the throat of the 

 black whale. The toothed whales are much more 

 voracious. The large spermaceti whale is a very 

 voracious animal, capable of swallowing seals, moder- 

 ately sized dolphins, and most fishes ; and it is said 

 to chase and capture the white shark with great 

 avidity, which, is a remarkable instance of a huge 



monster of the deep preying upon an exceedingly 

 voracious and daring one. The dolphins are chiefly 

 fishers, in the captures of which they are rather in- 

 discriminate ; but they are usually found in crowds 

 near the cod banks ; the larger one?, which are 

 usually styled grampuses, do not hesitate to prey 

 upon the latter or upon seals, and they are said to 

 tear the flesh and suck the blood of the whalebone 

 whales, though they keep a respectful distance from 

 the spermaceti whales. The common porpoise hunts 

 indiscriminately all fishes which are near the shores ; 

 and it is peculiarly destructive of salmon, especially 

 when they are ascending the estuaries of the rivers 

 for the purpose of spawning. It is not, however, very 

 easy to say what may, at all seasons of the year, be 

 the'food of animals but occasionally seen. 



System of circulation. The system of circulation in 

 the cetacea does not differ much in its general struc- 

 ture from that of land mammalia, and, indeed, the 

 chief difference is that which runs through the whole 

 structure, namely, a coarser, softer, and less compact 

 texture in the vessels of the cetacea; this is general, 

 and we might expect it to be so, for in every order 

 or other natural division of animals, if the division is 

 formed with sufficient ease, we may expect a unifor- 

 mity in the texture of all the parts. The chief one 

 here is, that the heart is softer, and indicates less 

 muscular action than that of land animals ; and from 

 this we may conclude that the circulation in the whale 

 tribe is slower. That they have as high, or even 

 higher temperature than land animals, is no argument 

 against a slower circulation ; because the heat is not 

 in proportion to any motion considered simply in 

 itself, but in proportion to the motion and the resist- 

 ance with which that motion meets, taken jointly. 

 Now, it is easy to see that an animal which has 

 generally more than the half, and sometimes the 

 whole of its body immersed in the water, which water 

 must exert a very considerable resistance or pressure 

 upon an animal of so great size ; it is easy how this 

 pressure may, with a slower circulation, produce as 

 high a temperature as a much more rapid circulation 

 would produce, if there wer eno other resistance than 

 that of atmospheric air. 



This is a consideration worthy of notice when we 

 come to consider the temperature of animals, and 

 also the effect that pressure has upon them. It is 

 well known that animals on high mountains, where, 

 the pressure of the atmosphere is greatly diminished, 

 are cold and languid in their circulation, and that 

 they are much more prone to become dormant than 

 animals which inhabit lower down ; and from this we 

 may safely conclude, that an animal under the pres- 

 sure of a fluid so much more dense than the atmos- 

 phere or water is, may produce a high temperature 

 with much smaller action of the system. There have 

 been various attempts at theories of animal heat, as if 

 it were brought about by some mysterious process, 

 connected with the function of breathing ; but any 

 one who has felt the burning heat arising from the 

 resistance offered to the circulation in the small 

 vessels, in the case of even a common whitlow on the 

 finger, may thereby obtain demonstrative evidence of 

 the real source of animal heat, sufficient to overturn 

 all the theories that ever were fancied or fabricated. 



The cetacea have two ventricles and two auricles 

 to the heart, and a pulmonic and systematic circula- 

 tion, just in the same manner as all the other mam- 

 malia. But there were once some inaccurate notions 



