82 



Papers from the Marine Biological Laboratory at Tortugas. 



Table 26 shows the decline in weight of two halves of a disk of Cassiopea 



frondosa deprived of its stomach. One of these halves was starved in diffuse 



daylight and the other in the dark from February 28 to March 18, 1912, 



at Montego Bay, Jamaica. 



Table 27. 



' Calculated from the formula y = 61(10.1673)*. 

 ^Calculated from the formula y = 57.5(1 0.14)^. 



Table 27 shows the decline in weight of two normal medusae of Cassiopea 

 xamachana starved each in one liter of sea-water, changed once in each 24 

 hours, and kept in the diffuse daylight of the laboratory at Tortugas, 

 Florida, from June 8 to 20, 1913. One medusa, A, was starved in sea- 

 water which had been passed through two glass funnels each holding two 

 sheets of Chardin filter paper. The other medusa, B, was starved in sea- 

 water, which, in addition to having been filtered through the aforesaid 

 Chardin filters, was also filtered through a bacteria-proof porcelain filter. 

 It appears that all food had been removed from the water by the Chardin 

 filters and the medusa in the bacteria-free sea-water starved somewhat more 

 slowly than the one in the sea-water which had not been passed through the 

 porcelain filter. 



DESCRIPTION OF PLATE. 



Fig. a. Cassiopea xamachana. The 6 medusae have been starved for 41 days in diffuse 

 daylight (see table 4). The recently caught, unstarved medusa in the 

 center of the aquarium is of nearly the same size that the smallest (shown 

 by the arrow) was when starving began. The dark-brown color of the 

 starving medusae is due to their densely crowded commensal plant-cells. 



Fig. B. Cassiopea xamachana which has been starved for 41 days in darkness. Origin- 

 ally its bell was 25 mm. wide; now it is only 4.5 mm. in diameter, and the 

 rim is turned upward and inward. The mouth-arms are each 3 mm. 

 long, and the mouths have disappeared by coalescence of the lips. The 

 medusa is still pulsating, a single rhopalium functioning. 



Fig. Ci. Normal medusa of Cassiopea xamachana. 



Fig. C2. Disk without stomach or mouth-arms. 



Fig. C3. The stomach and mouth-arms of the medusa, the disk having been cut away. 



