Respiration 101 



weight in air-breathing animals." There has also been an increase 

 in their vascularization. 



Respiration is essentially the same process in air as in water, and 

 in the ocean as in fresh water. Colosi (1927, 1930) has also empha- 

 sized the fact that organisms in passing from aquatic to atmospheric 

 media do not change their respiratory medium, since in all terrestrial 

 animals it consists of "a film of aqueous Uquid" that moistens the 

 respiratory surfaces and ^'serves as a path for oxygenation." This 

 "constancy of the respiratory medium" permits migration, during 

 ontogeny or phylogeny, from aquatic to terrestrial environments 

 "without the violent physiological crisis which would accompany an 

 excessive change in oxygen pressure." All organs take their oxygen 

 for respiration from one medium — water. "The physiology of res- 

 piration in fishes is the same as in lung-breathing animals" (Powers 

 et al.y 1932) . In man air which enters at 25 C. and has a humidity 

 of 35%, attains a humidity of 79% in the nose, and of 95 to 98% 

 in the lung (Perwitzschky, 1927) . Poikilothermic animals use 

 about the same amount of oxygen per gram per hour as those which 

 live in the ocean at the same temperature (Gjaja, 1922) . The 

 rate of metabolism is about the same in reptiles, amphibians, and 

 crustaceans, but in insects and homoiothermic vertebrates it is faster 

 (Krogh, 1916) . Poikilothermic animals need less oxygen at low 

 temperatures (Helff & Stubblefield, 1929), though many show sea- 

 sonal variations (Dolk & Postma, 1927) . Some poikilotherms, at 

 least, require less oxygen in salt water than in fresh water (Fox & 

 Simmons, 1933; Schlieper, 1933). The oxygen consumption of 

 barnacles in air depends on the salinity of their body fluids (Borsuk 

 8C Kreps, 1929). The alkaU reserves in the bloods of animals affect 

 ability to respire in various media. "A series of animals arranged 

 according to their alkali reserve suggests strongly the gradual transi- 

 tion from aquatic to terrestrial life" (Kokubo, 1930) . 



Marine fishes differ among themselves in ability to live in water 

 containing little oxygen and in respiratory rate. A toadfish (Op- 



