368 PLINY'S NATURAL HISTOET. [Book IX. 



sees that it is even exhaled*^ 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 an- 

 helation during the heat of summer, and at other times again, 

 a kind of leisurely gaping," 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*^ 

 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'*^ 

 grow in bulk. 



But the most convincing reason of all is, the undoubted fact 

 that fishes have the power of hearing'*^ 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 wdth certain particles.**^ However, let every 

 person form his own opinion on these subjects, just in such way 

 as he may think best. 



Neither the balsena nor the dolphin has any gills."*^ Eoth 



43 In the shape of vapour raised by the action of the sun. In accord- 

 ance with this opinion, Cicero says, De Xat. 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." 



4^ But, as Hardouin remarks, this act on the part of the fish is caused 

 as much by the water as the air. 



45 As Hardouin remarks, this is a somewhat singular notion that sleep 

 is produced by the action of the lungs. 



4« 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 

 ])ossibly be, that the moon has an influence on bodies through the medium 

 (•f the air, in accordance with the notion of the ancients that the respira- 

 tion was more free during the time of full moon. Littre says, that Pliny's 

 meaning is, tliat since the influence of the moon is able to penetrate the 

 waters, the air and the vital breath can of course penetrate them also. 



4' See B. X. c. 89, where this subject is further discussed. 



48 " Infectum aera." 



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

 C.2. 



