Use of Concentration to Discover Why Camels Can Go Weeks Without Water
There are many reasons why camels can survive the desertís arid conditions:
In the 1950ís, Knut Schmidt-Nielsen and his wife injected a harmless dye in to a camelís bloodstream. They waited a while for the dye to distribute itself evenly. Then they took a blood sample and measured the concentration of the dye. Then the camel went 8 days without drinking in the desert heat. Although it lost a lot of weight (over 40 litres of water), the concentration of the dye in the blood revealed that the blood had only lost about 1 litre of water. In other words the rest of the water had been lost from tissues.
This is the kind of calculation that the Nielsens used:
Suppose that the original concentration of the dye had been 0.0495 g/L in 100 L* of blood. If the concentration of the dye had then increased to 0.0500 g/L, using C1V1 = C2V2,
0.0495(100) = 0.0500V2, would reveal V2 to be 99 L, a change of only 1 L.
*How did they know that the camel had a 100L of blood? Let's say they had originally injected 8.0 mL of 619 g/L of dye. After even distribution of the dye(before the camel went 8 days without drinking), the concentration became diluted to 0.0495 g/L, then C1V1 = C2V2,(0.0080) = 0.0495(0.008+V2), would reveal V2 to be about 100 L.
Scientific American. The Physiology of the Camel. December, 1959.
Picture from George Holton, The National Audubon Society Collection/Photo Researchers