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on the subject of their circulation, which are still 

 retained in many of the books made up by com- 

 pilers, who, as they must go back till they clear the 

 time of copy-right, are, very often, the means of 

 digging old errors out of their graves, to the injury 

 of beginners in science. The error in the present 

 case is this : there is, in the fetus of all the mam- 

 malia, while it remains in utero, an opening in the 

 partition which separates the two ventricles of the 

 heart ; and the blood which, in the animal after it has 

 begun to breathe, is carried to the lungs, is not so 

 carried in the uterine foetus, but returns through this 

 opening into the systematic ventricle, the lungs being 

 then inactive. This opening was called the foramen 

 ovule, and it was supposed and said that, in order to 

 enable a warm-blooded and air-breathing animal to 

 live under water, it was only necessary that this 

 foramen should be kept open, and the blood would 

 circulate, and all the functions of life be carried on 

 without breathing ; that, in tact, this foramen did 

 remain open in the cetacea, and also in all the 

 animals which used to be called " amphibious," and 

 this was the cause why they could live under water. 



No error can be more subversive of all that we 

 know of the physiology of animals than this. The 

 fa'li/ti in ulcro docs not carry on the functions of life 

 there, because of the circulation of the blood through 

 the foramen ovale ; and that opening exists only be- 

 cause the lungs are not in action ; and the reason 

 why their action is not necessary is, that the blood of 

 the foetus undergoes the necessary aeration in the 

 placenta ; but, the moment that the umbilical cord is 

 divided, and there is no more aeration by means of 

 that viscus, the lungs act, and the foramen closes, 

 and though the opening were to remain, the circula- 

 lation continued through it would be death rather 

 than life to the animal. It is not the mere circula- 

 tion of the blood that is necessary to a healthy state 

 of the animal ; it is that the blood may obtain the 

 proper action of the air, whether by lungs or any 

 other apparatus ; and if lungs be the organs, there 

 can be no circulation under water, or anywhere else 

 than in the free air. That the whales can remain 

 longer under water than land animals is true ; and 

 they are enabled to do so, partly by the valves which 

 shut down upon, and close the breathing passages, 

 and partly also by the less energetic action of their 

 system, which, as we have said, is to some consider- 

 able extent compensated by the re-action of the 

 dense fluid in which they are always, in part at least, 

 immersed. 



Frogs and other batrachian reptiles, which breathe 

 with gills in the early stage of their being, and by 

 lungs after they undergo their change, cannot breathe 

 under water after they have got their lungs, any 

 more than these animals which never have gills or 

 breathe in that fluid. 



And here it is worthy of remark, as a point which 

 is riot usually adverted to, that all placenta! mam- 

 malia undergo a metamorphosis at their birth, not 

 very dissimilar to that which frogs undergo, when 

 they change from the tadpole to the perfect frog. 

 We know less of the physiology of marsupial animals 

 which have a. double gestation one in the internal 

 uterus and one in the marsupium, but we can trace 

 clearly m them, a sort of intermediate character be- 

 tween the placcntal mammalia and oviparous animals ; 

 and when we survey the whole of the living tribes, 

 and scan the growing ones, there breaks in upon, us 



a very wonderful light, dim in many places no doubt, 

 but still, such as we may yet see beam on the whole 

 economy of nature, and disclose many principle?, 

 and clear up many doubts. It is this : every living 

 Ct>ld growing thing, animal or vegetable, w, in aoitie early 

 stagf of its being, so organised an that it can breathe in ft 

 /i(/ni(f, whatever may be its mode of breathing when full 

 grown. 



This principle has not been marked out, nor 

 hitherto, we believe, so much as even enunciated; 

 but it is one, the consideration of which we earnestly 

 recommend to those readers who are fond of studying 

 the working of nature, and we are strongly persuaded 

 that they will find it true in every case. In that of 

 the fa- 1 us in ulcro, of all the mammalia, there is not 

 the least doubt. The membranes by which it is 

 enveloped are perfectly air-tight, so that the free-air 

 cannot reach the foetus. We know that the lungs 

 are never inflated till the membranes are ruptured ; 

 we know, also, that there is a distinct partition 

 between the mother and the young nay, that this 

 partition is double, and that not only the whole of it, 

 but each of the pellicles of which it is made up, is 

 perfectly air-tight. The consequence is, that there 

 can be no breathing of the free air in the case of 

 the foetus of even the land mammalia, and that there- 

 fore there must be sought some use of the fluids 

 contained in the membranes which has not yet been 

 attended to. 



We very much suspect, nay, we are quite sure, 

 that the same will be found to be the case with the 

 whole of the animated races, and even in the gene- 

 ration of the seeds of plants, until they put. forth 

 their radicle and plumula, or otherwise display to 

 the free air some organ upon which that air can act. 

 We mention this incidentally, and of course briefly ; 

 but it is a subject of far greater importance than any 

 one connected with, or forming part of the history or 

 physiology of any one order, or any one class of 

 animals. 



St/stcm of Sensation. In this system, also, the 

 cetacea follow the law of, and are in reality mam- 

 malia. It is true that, in the larger species, and 

 especially in those with very large heads, the mass of 

 the brain bears a small proportion to that of the 

 animal, and especially to that of the head, but what 

 is of it is well developed, and it displays a distinctly 

 fibrous texture. The whole mass of the brain is 

 proportionally largest in the porpoise, and smallest 

 in the great spermaceti whale ; but, on the other 

 hand, the spinal cord is larger in that whale than in 

 any of the others that is, larger in proportion. The 

 nerves arc also very analogous to those of the other 

 mammalia, only, the proper olfactory nerves are 

 wanting, and it is probable that the animals have not 

 much sense of smell, as indeed, from their habits, 

 they cannot have much use for it. There are some 

 circumstances, however, which render it probable 

 that the animals are not wholly destitute even of this 

 sense. 



As the whole surface of the skin is beset with 

 papilhe.it is probable that the cetaeca have a general 

 sensation of touch all over their bodies, though, from 

 the thick layer of soft fat which is accumulated under 

 the skin, it cannot be supposed that this sense is very 

 delicate. 



The whole structure of the tongue, its size, its 

 softness, its moistness, and the apparently great use 

 of it in enabling them to feel (rather than taste) what 



