Law Governing Loss of Weight in Starving Cassiopea. 



6i 



Table 3. 



Medium in which medusae were starved 

 and conditions of the experiment. 



Normal medusae each in 6 liters or more 

 of doubly filtered sea-water changed 

 once in every 24 hours. 



Medusae regenerating bell-rim but with 

 stomach and mouth-arms intact, each 

 in 6 liters or more of doubly filtered 

 water changed once in each 24 hours. 



Regenerating disks with stomach and 

 mouth-arms removed, each in 6 

 liters or more of doubly filtered water 

 changed once in each 24 hours. 



Normal medusae in 400 c.c. of doubly 

 filtered water changed once in each 

 24 hours. 



Normal medusae in large quantities of 

 doubly filtered constantly changing 

 sea-water. 



Normal medusa in 6 liters of sea-water 

 sterilized by heating it to 71 C, and 

 then cooling it to normal tempera- 

 tures. The water being changed once 

 in each 24 hours. 



Value of a when medusae are 

 starved in diffuse day- 

 light of laboratory. 



0.046 to 0.075; av. 0.0567. 



0.0681 to 0.0689; av. 0.068s 



0.06 to 0.1034; av. 0.0815. 



0.1145. 



0.1015 to 0.15; av. 0.125. 



o.oss 



Value of a when medusae are 

 starved in dark. 



0.0639 to 0.075; av. 0.069s 

 0.0511 to 0.0538; av. 0.052 



0.074 to 0.0937; av. 0.0892 



0.1 



0.165 to 0.185; av. 0.175. . 



Tables re- 

 ferred to. 



4 to 10 and 

 19 to 25 



18 to 25 



II and 12 

 IS and 16 



17 



The relative rates of starvation both in darkness and in diffuse dayhght, 

 shown by medusae under other conditions, are as follows, the results being 

 derived from table 3. 



Normal medusae in large amounts of stagnant water i.o 



Medusae regenerating their bell rims, but with stomach and mouth- 

 arms intact 0.96 



Medusae starving without stomachs 1.27 



Normal medusae in small aquaria of 400 c.c. capacity 1.7 



Normal medusae in constantly running water 2.4 



Normal medusae in water sterilized by heating it to 71" C i.o 



Although for the first week or more the regenerating medusae generally 

 lose weight more rapidly than do the normal animals the final rate of 

 starvation appears to be practically the same in normal and in regenerating 

 medusae provided their stomachs be present, and this is in accord with the 

 well-known converse fact that the rate of regeneration is independent of the 

 food-supply, starving animals regenerating quite as rapidly as well-fed ones. 



In this connection it appears from an inspection of the curves accom- 

 panying tables 4 to 27, that if the starving medusae lose but little weight for 

 a day or two, a succeeding period of abnormally rapid loss is apt to ensue 

 and thus the animals tend to follow the theoretical curve y = W(i a)'. 



Cassiopea lives in shallow lagoons of semistagnant water, where it lies 

 fully exposed to the hot sun and, as table 3 shows, it loses weight slowly 

 when kept in quantities of water of about 6 liters per animal in aquaria the 

 water of which is changed only once in each 24 hours. If the water be 

 changed constantly, however, or the medusae be kept in running water, they 

 starve more rapidly than if maintained in stagnant water. 



It will be recalled that Allen and Nelson^ found that if sea-water be 

 heated to 70 C. practically all life within it is killed, and the water 

 remains sterile unless reinfected. 



Allen, E. J., and E. W. Nelson (1910). Quarterly Journal of Microscopical Science, London, vol. 53. 

 pp. 361-431; also. Journal of Marine Biology Association, vol. 8. 



