Law Governing Loss of Weight in Starving Cassiopea. 65 



unfed or poorly nourished, and that the larvae became amoeboid and changed 

 into creeping plasmodia without cell boundaries, Thacher^ also observed a 

 process of degeneration in hydroid colonies of Eudendrium, Pennaria, and 

 Campanularia kept in aquaria. The polypi tes of these forms are absorbed, 

 the degenerating cells of the entoderm and finally the ectoderm of the 

 hydranths being turned into the digestive tract of the stem. 



By contrast with the few studies upon invertebrates many researches 

 have been conducted upon the metabolism of matter and energy in the body 

 of starving vertebrates. To properly review this literature would carry us 

 too far afield and indeed a text-book would be required for the purpose, but 

 the literature of the subject, in so far as it relates to man and the higher 

 vertebrates, has been exhaustively reviewed by Atwater and Langworthy 

 (1897) in their "Digest of Metabolism Experiments" (434 pp.. Bulletin No. 

 45, United States Department of Agriculture, OfRce of Experiment Sta- 

 tions). One should also consult such later works upon vertebrates as At- 

 water and Benedict (1903), Benedict (1907), Weber (1902), Ergebnisse der, 

 Physiologic; Schaefer (1898), Text Book of Physiology, vol. i, p. 891; 

 Manca (1902), Pembrey and Spriggs (1904), Abderhalden, Bergell, and 

 Dorpinghaus (1904), Hatai (1904), Cathcart and Fawsitt (1907), and 

 Maignon (1908), and others referred to by these authors, the list of papers 

 cited by Pembrey and Spriggs in the Journal of Physiology (Cambridge, 

 vol. 31, pp. 320-345), and by Benedict (1907), being especially enlightening. 



EXPLANATION OF THE TABLES. 



In the figures accompanying tables 4 to 25, when the medusae are starved 

 in darkness their observed weights are indicated by black dots ; when starved 

 in the diffuse light of the laboratory their weights are shown by circles. 



Tables 4 to 25 refer to Cassiopea xamachana and table 26 to the allied 

 species C. frondosa, which follows a law in its starvation similar to that of 

 C. xamachana. 



Table 4 shows the decline in weight of 6 normal medusae of Cassiopea 

 xamachana starved 41 days in filtered sea-water, in the diffuse light of the 

 laboratory, at temperatures ranging from 27.3° to 30.1° C, from June 18 to 

 July 29, 191 1, at Tortugas, Florida, The medusae were kept in a 6-liter 

 glass aquarium, the water being changed once in every 24 hours. Compare 

 this with table 10 to see the effect of darkness upon medusae subjected to 

 conditions as nearly as possible identical with the medusae starved in day- 

 light. The curve 3' = 75(1 — 0.075)* does not accord well with the facts, 

 but the curve represented by y = 75(1 — 0.058)^ accords fairly well with 

 the observed decline in weight up to the sixteenth day, after which it 

 departs more and more widely from the observed weights and is unsatis- 

 factory. (See table 5.) 



1 Thacher, H, F, (1903). Biol. Bulletin Woods Hole, vol. 4, pp. 96-98. 



