341 
HOW FISHES BREATHE. 
By JOHN C. GALLON, M.A., M.R.C.S., F.L.S. - 
Late Lecturer on C omparativ e Anatomy at Charing Cross Hospital. 
[PLATE LXXVI.] 
“ Solemne est Naturae, unica actione, et eodem instrumento plura commoda 
acquirere. Hoc praecipue in respiratione observatur — Bobelli. 
T HE common expression, “ to drink like a fish,” contains 
much latent truth, though this animal seems hardly, at 
first sight, to furnish an apt illustration of excess, seeing that, 
living as it does in water, it must perforce practise temperance, 
if by temperance abstinence from all fermented fluids be 
understood. 
Nevertheless, a fish “ drinks hard ” — as often, say, as twenty 
times in a minute* — but not in the sense that we understand by 
drinking, as a compensation for loss of water from the body 
by various means, ard through various channels, or merely to 
satisfy, toper-like, the capricious cravings of a u thirsty soul.” 
No ; most of the water which enters so constantly into its. 
mouth never reaches the stomach, but, after rippling over those 
beautiful organs, its gills, passes straightway away from the 
body, having, in this short period, by purifying the blood, 
renewed the lease of a life which is held by a tenure only too 
slender — a result the converse of which more commonly attends 
the more potent draughts, often as periodic, but luckily less 
frequent, of certain 66 higher animals.” 
As the subject of the present article is rather the mechanical 
than the minutely anatomical, physiological, and chemical 
processes involved in the breathing of fishes, a very brief 
summary of the circulation of their blood must suffice. 
The blood, which has become befouled and impoverished in 
its journey through the various organs of the body, finds its way 
to the heart — the great pumping-station of the physiological 
sewage in the body of a fish — by means of two longitudinal 
trunks, one on either side, which meet, each through the 
medium of a transverse channel, in a large antechamber, 
* A pike which the author timed, the other day, at the Gardens of the 
Zoological Society was gulping in water at about this rate. 
VOL. X. — NO. XLI. A A 
