288 Life in the Deep Sea. 



kind, but if the pressure from within can equal that from 

 without, its physical force would not necessarily destroy any 

 organism exposed to its effects. Dr. Wallich judiciously indi- 

 cates the difference between certain well-known experiments 

 and the conditions under which deep sea creatures live. Thus, 

 "in the case of pieces of wood and meat, and corked bottles con- 

 taining air, which have been sent down to great depths, in 

 order to demonstrate the effects of pressure, it is evident that 

 precisely those conditions are present which are never to be 

 met with in creatures constituted to live under it. In short, 

 they prove too much ; for they prove clearly that, in defiance 

 of all obstacles, a state of equilibrium is rapidly engendered 

 between the interior and the exterior of the wood, the mutton, 

 and the bottles, and that whensoever this takes place no further 

 change is experienced. If suddenly submerged, that is to say, 

 before the pressure has time to overcome the resistance of the 

 cellular and fibrous tissues of the two first, and of the earth 

 employed in the last, diminution of bulk and consequent com- 

 pression of the structure must inevitably result; but, on the 

 other hand, if the submergence be gradual, the diminution in 

 bulk is by no means a necessary consequence, and the change 

 brought about is a simple displacement of a lighter medium by 

 a heavier, according to a well known law of fluids." This is no 

 doubt right in principle, but scarcely correct in detail, as all 

 portions of an organism may not be thus permeable, and those 

 which the heavier fluid cannot penetrate, must be subject to 

 the pressure which it exerts on all sides. It will, however, be 

 admitted without difficulty, that marine animals like the star- 

 fishes or the annelids of Dr. Walliclr's dredgings would not be 

 injured by the weight of water, if gradually submerged ; and 

 having disposed of one difficulty of deep sea life, let us turn to 

 another, in which the function of respiration is concerned. 



Some valuable experiments on board the French ship 

 " Bonite" give us an insight into the quantity of gaseous matter 

 existing in the water at different depths, which appears, within 

 the limits investigated, to increase as the surface is left behind. 

 From these investigations, and on other grounds, Dr. Wallich 

 concludes that " since the tendency of fluids to absorb gaseous 

 bodies is constant under all circumstances, although, as already 

 stated, the quantity they are capable of appropriating increases 

 with the pressure, it follows that the deeper the stratum of 

 water, the greater must be the amount of gaseous matter held 

 in solution by it." But the ocean is not a closed vessel, in 

 which the liquid and the gas are squeezed together without 

 possibility of escape, and if water at a mile down contains more 

 air than the strata above it, the effect must be produced by the 

 operation of a powerful attraction increasing with the compres- 



