A N A B A S. 



99 



of torpidity induced by drought as well as by cold. 

 As long- as there is food for insects, there is also food 

 for lizards in those arid seasons ; but when the sur- 

 face for a great extent, is reduced to mere sand, the 

 Hies and other insects perish, and the lizards burrow 

 in the sand and become dormant. Whether any of 

 the fresh water fishes of tropical countries become 

 dormant in the remaining waters during the time of 

 the drought, in the same manner as, with us, eels be- 

 come dormant in the ooze on the shores during the 

 cold of the winter, is a point which, though interest- 

 ing, has not been ascertained. It is at least probable, 

 inasmuch as the numbers of fishes belonging to this 

 curious family, to be met with any where during 

 the dry season, bears no proportion to those which 

 appear almost contemporaneously with the rains ; and 

 the intervals between one portion of water and another 

 tire often too great either for the supply of water in 

 the labyrinths to moisten the gills, or for the loco- 

 motive powers of the animals. The progressive mo- 

 tion of the genus under consideration has not been 

 very carefully noticed ; but there is no doubt (from 

 what has been observed of analogous genera in 

 Guiana) that the chief organs of motion on level 

 ground are the pectoral fins, by the action of which 

 the animal wriggles along something after the fashion 

 of a seal. The fish seems to have some means of 

 measuring distance by the eye, even out of water where 

 the bank is low ; if the state of the water warns them 

 that it is time to depart, they will leap clear out of 

 the water and on the top of the bank ; but if the bank 

 is more elevated, they climb, in which progress they 

 bring their fins and also their tails into action. 



There is here a very curious point, which appears 

 to show that though the eyes of fishes are differently 

 formed from those of man or the other land animals, 

 they are subject to some optical deceptions. Those 

 fishes which come upon land in their migrations, 

 whether they work chiefly by their fins, as the anabas 

 and the analogous genera, or by wriggling, as is the 

 case of eels, never attempt to leap at banks of earth 

 or breasts of dry rock which are too high for them, 

 while those which ascend in the water only are in- 

 cessant in their attempts, even where those attempts 

 seldom succeed. In the season when instinct leads 

 the salmon to ascend the streams, they may, in many 

 of our own rivers, be found making continual at- 

 tempts to surmount those cascades above which a 

 single salmon has never been found ; from which it 

 should seem that the descending water deceives their 

 vision, much in the same manner that we imagine 

 that the sea billows are rolling ashore, even when 

 the whole mass of the water is ebbing away with the 

 tide. 



It is worthy of remark that there seems to be some 

 analogy between the labyrinths of these fishes and the 

 water-cells in the stomach of the camel. It is true 

 that the animals require the water for very different 

 purposes, or at least for very, different immediate 

 applications. To the camel it answers the purpose of 

 drink; but to the fish it immediately answers that 

 of respiration ; and though "to drink like a fish" be 

 a common saying, it is very probable, nay, it is al- 

 most certain, that fishes do not drink. Even in land 

 animals, though the fact has been but little attended 

 to by writers on physiology, it should seem that the 

 grand purpose of drinking is to moisten the organs 

 of respiration. At all events;, the great waste of 

 aqueous humidity is by the lungs ; and when one 



is parched with thirst, the breathing is always pain- 

 fully hot and laborious. If this view of the matter 

 is correct, and it agrees well with the observed facts, 

 there is much less difference in essential act between 

 breathing by lungs and breathing by gills, than the 

 usual theories on the subject would lead us to suppose. 

 It has already been mentioned (see AIR) that fishes 

 and other aquatic animals do not, and cannot, 

 separate the oxygen which is necessary for the 

 arterialisation of their blood from the water by a direct 

 and immediate decomposition of that liquid. They 

 breathe the air which is in the water, and if the 

 water contains no air they are suffocated as cer- 

 tainly and almost as speedily as if there were no 

 water there. The quantity of air which they re- 

 quire for that purpose is much smaller than that 

 which is necessary for mammalia, as birds, and the 

 surface at which they receive air is much more 

 limited ; and as that surface is moistened by the 

 water in which they for the most part reside, they 

 do not require that apparatus which, though it has 

 not been clearly pointed out by anatomists, land 

 animals possess for the moistening of their breathing 

 surface. But, in all cases, it appears that if, by any 

 means, the breathing surface can be kept duly moist- 

 ened, respiration, and with that all the functions 

 of life, can go on in the animal ; and that, as long as 

 the supply in the labyrinth of the one, or the cells 

 of the other lasts, the anabas can live on land, and 

 the camel endure the burning heat of the desert. 



There is another fact which throws a good deal 

 of light upon this most important but rather novel 

 view of what may be considered as the most im- 

 portant point in the whole range of natural history. 

 Surface fishes, such as the herring and the mackerel, 

 which live in that portion of the waters which may 

 be considered as abounding much in air, die almost 

 the instant they are taken out of the water; but 

 bottom fishes, such as the eel, will live a longer time ; 

 and in these last, the breathing surface is always less 

 extended, and what may be called the vital action 

 less energetic. 



It does not appear that fishes have any organi- 

 sation, by means of which they can bring, from any 

 other part of their bodies, a supply of water for the 

 moistening of their gills. It has been said that there 

 is no reason to suppose that they drink ; and there 

 is as little reason to suppose that they absorb water 

 at the surface of their bodies, or any part of it, the 

 breathing surface excepted ; and this accounts for the 

 speediness of their death in the dry air, and also for 

 the necessity of the supply of water in the labyrinths 

 of the family under consideration. 



With land animals, the case is quite otherwise. 

 Different species have, no doubt, different absorptive 

 powers; but of all warm-blooded animals it may be 

 said that they have some means of absorbing mois- 

 ture from the air when they are deprived of it as 

 drink ; and we know how readily all the parts of the 

 body sympathise with and give up their humidity to 

 the lungs when those organs are panting in agony. 

 The rapid breathing in fatigue or in fever, parches the 

 body ; and parches it not by perspiration, sensible or 

 insensible, at the surface (for that, when it comes, 

 brings relief), but by a drain of moisture internally 

 from the other parts, to moisten the lungs, which, in 

 proportion as they labour faster, require an increased 

 supply. 



The breathing and circulation of the blood are so 

 O2 



