XIII. 
THE PHYSIOLOGY OF DEEP-SEA LIFE. 
I HAVE no observations of my own to present in regard to 
the composition of sea-water. For convenient reference, the 
interesting results of the chemists of the “Voringen” and 
“Challenger” are here given in a condensed form. 
As early as 1872, the chemist of the German expedition to 
the North Sea and the Baltic, Dr. Jacobsen, successfully ex- 
tracted at sea the gaseous elements of sea-water. The appara- 
tus which he used was subsequently adopted by other expedi- 
tions, with but little modification. 
On board the Norwegian vessel, the * Vóringen," Dr. Tornöe 
employed a machine modified by Captain C. Wille, consisting of 
a spiral tube nearly five feet in length, open at both ends, 
through which water passes freely as the instrument is lowered. 
When raised the ends are closed by conical valves worked by 
screw fans, which, as in the case of the Sigsbee cup, revolve in 
one direction while going down, and in the opposite while 
ascending, the valves closing in a short distance. 
The difficulty of making an analysis of gases on board a 
small vessel is very great, though the separation of the gases 
from the sea-water is not a hard process, and is accomplished 
by an apparatus not materially different from that employed 
by Bunsen. But the modification made in this apparatus by 
Dr. Behrens (Fig. 193) is all-important, and renders the opera- 
tion comparatively easy. The attempt made on the “Blake” 
with Bunsen's apparatus failed, partly from want of room, and 
partly from my want of familiarity with the work. 
The apparatus is made up of a flask for the reception of the 
sea-water to be tested, and of a bulb-tube connecting with the 
