EFFECT OF WATER PRESSURE ON BIOPLASM 253 



and thus a flora does not exist excepting bacteria and fungi, while 

 the fauna lives in darkness, except for a dim phosphorescent glow 

 produced by the radiolaria and other animals which compose it. 

 Water is a bad conductor of heat. So that the temperature in 

 the tropics drops from 80 F. at the surface to 0-5 F. at a depth 

 of 5000 ft. (Regnard). The deep-sea animals prey upon each other, 

 and upon the debris of dead organisms which falls in a ceaseless 

 shower from the higher strata of the ocean. 



At 7000 ft. the dredge of the Challenger netted no less than 

 200 specimens, including 78 species of fish, Tunicates, Crustaceans, 

 Molluscs, Echinoderms, Worms, Ccelenterates, and Protozoa. The 

 species were much the same as those in shallow water, but were 

 even more abundant. The abysm yielded no primeval forms of 

 life ; the deep-sea fauna appears no more ancient than an}^ other. 

 The colour of the animals are in many cases startlingly brilliant, 

 and, owing to the darkness of the depths, have not been evolved 

 for the purposes of protection. The eyes are either rudimentary 

 or enormous in size, while the tactile organs are greatly de- 

 veloped in the form of long barbels, fins, or antennae. The skin, 

 bones, shells are generally soft, and scales absent or little de- 

 veloped. Most of the animals show phosphorescence, and in some 

 as the deep-sea angler fish a phosphorescent light is suspended 

 as a bait over the gaping jaws of the fish. 



Regnard has studied the effect of enormous pressures of water 

 on all kinds of life. He used a hydraulic pump, and a small 

 steel pressure chamber fitted with thick quartz windows and 

 illuminated with the arc light. He found bacteria and yeasts at 

 700 atm. produced very little fermentation, so that urine, milk, 

 meat, &c., kept sweet for days. He says that softened but never 

 putrid dead fish have been brought up in the sounds, which are 

 ingeniously contrived to open and shut, and collect samples at the 

 bottom of the sea. Certes has obtained aerobic cultures from all 

 samples of sea- water obtained with due precautions at 500 to 

 5100 m. The existence of bacteria at any depth is thus assured. 

 Possibly the deep-sea bacteria have become acclimatised to the 

 pressure. Roger found that bacteria coli and staphylococcus 

 are not killed by exposure to the enormous pressure of 2903 atm. 

 (3000 kg. to the sq. cm.), while anthrax in its asporogenous but 

 not in its sporogenous form deteriorated in virulence after such 

 exposure. 



