July 26, 1895.] 



SCIENCE. 



95 



its lowest density in the equatorial region. 

 Accorduig to the hypothesis, therefore, of 

 the general vertical oceanic circulation 

 (which is true, but not as depending upon 

 temperature alone) , and to the superadded 

 hypothesis that the excess of precipitation 

 in the southern hemisphere causes the thrust 

 of sub-marine cold water into the Atlantic 

 and North Pacific, we should find, what we 

 do not find, on account of that very excess 

 of precipitation in the sou.thern hemi- 

 sphere — the surface waters receding every- 

 where south of the equator, from the equa- 

 tor towards the southeast, to be of very 

 low specific gravity ; which contradicts the 

 statement premised with reference to the 

 specific gravity of the surface waters on 

 each side of the equator, which statement 

 truly represents the facts of the case. 



As long as the earth under its present 

 physical conditions shall endure, the move- 

 ments of the ocean must remain as they now 

 exist, passing through phases of maxima 

 and minima of volume and velocity and os- 

 cillation in direction, dependent upon their 

 astronomical and ten-estrial relations. The 

 present oceanic forces are, in fact, huge hy- 

 draulic engines, worked by nature from the 

 north pole and the south, nor less from the 

 equator and the revolution of the earth. 

 The Gulf Sti'eam, Avith the analogous Japan 

 Cui-rent, is merely one of the two greatest 

 products of that machinery, the flow from 

 its colossal pump, in the direction of its dis- 

 charging tube and the general circiilation 

 of the ocean, partially actuated by the 

 earth's rotation and by the sun-generated 

 winds, being ceaselessly engaged in life-giv- 

 ing and life-aiding agency on the globe. 

 R. Meade Bache. 



PHYSIOLOGY IN 1894. 



No striking discovery in physiological 



science was made in the year 1894, and 



yet a large amount of substantial work has 



been accomplished both at home and abroad. 



Only a few of the more remarkable re- 

 searches can be here referred to. It has long 

 been known that the swimming or air blad- 

 der of sea fishes contains a much larger per- 

 centage of oxygen than exists in atmos- 

 pheric air. The amount maj' rise as high 

 85 per cent. The mode of storage of this 

 large amount of oxygen has always been an 

 interesting question with physiologists, 

 taken in connection with the very small 

 amount of oxygen in sea water. Light has 

 been shed on this problem by the ingenious 

 researches of Professor Bohr, of Copenhagen, 

 who has succeeded in tapping the air blad- 

 ders of codfish and of drawing o& the gas 

 by means of a trocar and an air-tight sjt- 

 inge. He found that the gas contained 

 52 per cent, of oxygen. In a few hours the 

 bladder was refilled apparently by a process 

 of secretion of gas from the blood in the 

 capillaries on the wall of the bladder, and 

 in one experiment the gas thus secreted 

 contained no less than 80 per cent, of oxy- 

 gen. Puncture of the air bladder always 

 caused increased secretion of oxygen, but 

 after section of the nerves supplying the 

 organ the evacuated bladder was not re- 

 filled with gas. Thus the formation of the 

 gas in the air bladder, which corresponds 

 to the lung of air-breathing animals, is a 

 true secretion of a highly oxj^genated gas- 

 eous mixture, and the secretion is evidently 

 to some extent under nervous influences. 

 These observations are very interesting 

 when taken in connection with the hy- 

 drostatic functions of the swimming blad- 

 der. "When a deep sea fish descends from 

 near the surface the air bladder is com- 

 pressed and the body is reduced in size, but 

 to bring the body into equilibrium with the 

 water the fish secretes gas in the air blad- 

 der so as to distend it and bring back the 

 body to the original size. This newly- 

 formed gas consists chiefly of oxj^'en. 

 These experiments by Professor Bohr tend 

 generally to support the theory that the 



