TRANSACTIONS OF THE SECTIONS. 
81 
this and other branches of the botany of Ireland at the next meeting 
of the Association, this communication is omitted, as well as other 
notices of the same nature by Mr. Babington, Mr. Curtis, and Pro¬ 
fessor Graham. 
Various other notices connected with the subjects of the papers 
were received from Dr. Coulter, Professor Graham, Mr. Curtis, 
Colonel Sykes, Mr. Fox, Mr. Waterhouse, Mr. J. B. Yates, Dr. 
Traill, Mr. Haliday, and Mr. Marshall. 
MEDICAL SCIENCE. 
On the Peculiarities of the Circulating Organs in Diving Animals . 
By John Houston, M.D ., M.R.I.A ., fyc. &>c. 
The circulation of the fluids in living animals, though mainly car¬ 
ried on by the influence of the vital powers, is nevertheless to a cer¬ 
tain extent amenable to the general laws of hydraulics. Gravity, 
motion of the particles of the solids upon each other, the respiratory 
function, pressure on the surface of the body, all, under various 
modifications, promote or retard the movement of the fluids along 
their vessels. But of all the collateral circumstances exerting an 
influence of this nature, the action of the chest and lungs appears, in 
warm-blooded animals, to be one of the most important. Suspen¬ 
sion of respiration puts a stop to the circulation of the blood through 
the lungs ; this fluid under such circumstances stagnates in the ves¬ 
sels leading to these organs, and cannot pass forwards until air be 
freely readmitted: death in a few moments is the inevitable conse¬ 
quence of such interruption. Animals living in atmospheric air 
cannot exist under a state of suspended respiration so long as those 
whose natural habitation is the water. The most expert diver has 
never been known to remain submersed for more than two minutes 
at a time, whilst it is well known that the whale can remain under 
water for upwards of twenty. Now, the arrangement of the respira¬ 
tory and circulating organs in man and cetaceous animals, and the 
influence of these two systems on each other, being the same, though 
their powers of suspending respiration with impunity are very dissimi¬ 
lar, we naturally inquire, on what does this latter difference depend ? 
Independently of the suspension to respiration which occurs in 
these animals while under water, there is another cause operating, 
when at great depths in the ocean, to the prejudice of their circu¬ 
lating fluids, such as is never experienced by terrestrial animals, 
namely, pressure on the surface of their bodies by the water, increas¬ 
ing with the depth from the surface. A boat, as observed by Scoresby, 
when dragged to the bottom of the sea by a whale into which a har¬ 
poon was struck, became in a few minutes as completely soaked in 
every pore as if it had lain at the bottom of the sea since the Flood: 
after being raised again to the surface, by the whale returning “ to 
blow”, it could with difficulty be got into the ship on account of 
its great weight; and a fragment of it, when thrown into the sea, 
G 
