6. Chap. 6.-Whether Fishes Respire, And Whether They Sleep.

CHAP. 6.—WHETHER FISHES RESPIRE, AND WHETHER THEY SLEEP.

Balænæ have the mouth[1] in the forehead; and hence it is that, as they swim on the surface of the water, they discharge vast showers of water in the air. (7.) It is universally agreed, however, that they respire, as do a very few other animals[2] in the sea, which have lungs among the internal viscera; for without lungs it is generally supposed that no animal can breathe. Those, too, who are of this opinion are of opinion also that no fishes that have gills are so constituted as to inhale and exhale alternately, nor, in fact, many other kinds of animals even, which are entirely destitute of gills. This, I find, was the opinion of Aristotle,[3] who, by his learned researches[4] on the subject, has induced many others to be of the same way of thinking. I shall not, however, conceal the fact, that I for one do not by any means at once subscribe to this opinion, for it is very possible, if such be the will of Nature, that there may be other organs[5] fitted for the purposes of respiration, and acting in the place of lungs; just as in many animals a different liquid altogether takes the place of blood.[6] And who, in fact, can find any ground for surprise that the breath of life can penetrate the waters of the deep, when he sees that it is even exhaled[7] from them? and when we find, too, that it can even enter the very depths of the earth, an element of so much greater density, a thing that is proved by the case of animals which always live under ground, the mole for instance? There are other weighty reasons as well, which induce me to be of opinion that all aquatic animals respire, conformably to their natural organization; for, in the first place, there has been often remarked in fishes a certain degree of anhelation during the heat of summer, and at other times again, a kind of leisurely gaping,[8] as it were. And then, besides, we have the admission of those who are of the contrary opinion, that fishes do sleep; but what possibility is there of sleeping[9] without respiring as well? And again, we see their breath disengaged in bubbles which rise to the water's surface, and the influence too of the moon makes even the very shells[10] grow in bulk.

But the most convincing reason of all is, the undoubted fact that fishes have the power of hearing[11] and of smelling, two senses for the operation of both of which the air is a necessary vehicle; for by smell we understand nothing else than the air being charged with certain particles.[12] However, let every person form his own opinion on these subjects, just in such way as he may think best.

Neither the balæna nor the dolphin has any gills.[13] Both of these animals respire[14] through vent-holes, which communicate with the lungs; in the balæna they are on the fore- head,[15] and in the dolphin on the back. Sea-calves, too, which we call "phocæ,"[16] breathe and sleep upon dry land—sea- tortoises also,[17] of which we shall have more to say hereafter.

1. "Ora." Cuvier remarks, that it is not the "mouth of the animal but the nostrils, that are situate on the top of the head, and that through these it sends forth vast columns of water." Aristotle, in his Hist. Anim. B. i. c. 3, has a similar passage, from which Pliny copied this assertion of his.

2. Cuvier remarks, that these are the animals of the cetaceous class, which resemble the quadrupeds in the formation of the viscera, their respiration, and the mammæ; and which, in fact, only differ from them in their general form, which more nearly resembles that of fishes.

3. Hist. Anim. B. viii. c. 2.

4. "Doctrinæ indaginibus." This certainly seems a better reading than "doctrina indignis," which has been adopted by Sillig, and which would make complete nonsense of the passage.

5. Dalechamps states that Cælius Rhodiginus, B. iv. c. 15, has entered very fully into this subject.

6. Cuvier remarks, on this passage, that the mollusca have, instead of blood, a kind of azure or colourless liquid. He observes also, that insects respire by means of tracheæ, or elastic tubes, which penetrate into every part of the body; and that the gills of fish are as essentially an organ of respiration as the lungs. All, he says, that Pliny adds as to the introduction of air into water, is equally conformable to truth; and that it is by means of the air mingled with the water, or of the atmosphere which they inhale at the surface, that fishes respire.

7. In the shape of vapour raised by the action of the sun. In accordance with this opinion, Cicero says, De Nat. Deor. B. ii. s. 27, "The air arises from the respiration of the waters, and must be looked upon as a sort of vapour coming from them."

8. But, as Hardouin remarks, this act on the part of the fish is caused as much by the water as the air.

9. As Hardouin remarks, this is a somewhat singular notion that sleep is produced by the action of the lungs.

10. Hardouin asks, what this has to do with the question about the air which Pliny is here discussing? and then suggests that his meaning may possibly be, that the moon has an influence on bodies through the medium of the air, in accordance with the notion of the ancients that the respira- tion was more free during the time of full moon. Littré says, that Pliny's meaning is, that since the influence of the moon is able to penetrate the waters, the air and the vital breath can of course penetrate them also.

11. See B. x. c. 89, where this subject is further discussed.

12. "Infectum aera."

13. See Aristotle, De Part. Anim. B. iv. c. 13, and Hist. Anim. B. viii. c. 2.

14. Aristotle, Hist. Anim. B. i. c. 5.

15. Cuvier remarks, that these nostrils, or vent-holes, are placed somewhat further back on the head in the dolphin than in the whale; but at the same time they cannot be said to be situate on the back of the animal.

16. Or "seals." They will be further mentioned in c. 15 of the present Book.

17. Or "turtles," which are more fully described in c. 21 of this Book.