On Changes in the Sea and Their Relation to Organisms. 



241 



substance, we should make it proportional to the loss in surface rather 

 than loss in volume, since the loss in living matter seems to be propor- 

 tional to the loss in surface and the cassiopea seems to have no other 

 important store of food than its own protoplasm, the mesoglea appar- 

 ently functioning chiefly as a skeleton. 



Since the surface is proportional to the two-thirds power of the vol- 

 ume, we may assume that the protein is proportional to the two-thirds 

 power of the weight (the density remaining practically constant). 

 The protein equals 5.16 per cent of the two-thirds power of the weight 

 (calculated from Hatai's data on the assumption that protein is 16 per 

 cent N). The weight at the beginning of starvation was 100 grams and 

 the protein 1.107 grams; at the end of one day the weight was 94.4 and 

 the protein 1.07, being a loss of 37 mg. of protein. If we assume that 

 1 mg. of protein is equivalent to 4.4 cal., the metabolism the first day 

 would be 163 calories, although I found it to be 336 to 342 calories. 



Although these calculations are only approximate, since starvation 

 is a little greater the first day than calculated by the formula, this 

 great difference indicates that the burning of protein does not account 

 for all of the heat. Since living cells contain lipoids or lipo-proteins 

 and carbohydrates or glyco-proteins, it seems probable that proteins, 

 carbohydrates, and lipoids are burned. The mesoglcea has not been 

 analyzed separately, but is largely sea-water, with possibly a trace of 

 glyco-protein. It probably has little calorific value, since the use of a 

 store of food would cause a relatively greater metabolism in large starv- 

 ing cassiopeas than was actually observed. 



Since the lining of the alimentary tract is not at the surface of the 

 cassiopea and O 2 must diffuse through at least a millimeter of tissue to 

 get to it, it was decided to pull off the manubrium and study the metab- 

 olism of the umbrella. The umbrella is disk-shaped, is covered on both 

 sides by epithelium, and pulsates, thus circulating the water. The 

 wound made by removal of the manubrium is of small area and is 

 covered by an epithelium within a few hours, and the umbrella will 

 live as long as a starving cassiopea. Some rough determinations 

 indicate that the respiration of the umbrella is only about a fourth as 

 great as that of the whole cassiopea. Table 17 records the measure- 

 ments on 3 cassiopeas and on their umbrellas after removal. 



TABLE 17. 



