4Q 



INANITION AND MALNUTRITION 



Mayer ('14) made a more extensive and detailed study of the inanition 

 changes in the same species of Cassiopea. The body weight decreases according 

 to the formula: 



Y = W(i- a)" 



W representing the initial body weight, Y the body weight after X days of 

 starvation, and a (the "index of katabolism") being the fairly constant fraction 

 of the existing body weight which is lost in any single day. 



The rate of starvation varies according to circumstances. If the rate for 

 the normal medusa in large aquaria of filtered stagnant sea-water is taken as 

 1.0, the rate in small aquaria (400 cc.) is 1.7; in running water, 2.4. For 

 starving medusae regenerating their bell-rims, the rate is 0.96; if starving with 

 stomachs removed, 1.27. In general the starving medusae regenerate as 

 rapidly as the well-fed. 



Bell rim 



Bell rim 



lsS4 



Arnvj" 



Yiq.lt 



F1$.D 



Arms" 



F4I4 



Lateral view, 



natural 



Fig. 12. — Normal medusa of the jellyfish, Cassiopea xamachana. 

 size. (After Mayer '14.) 



Fig. 13. — Medusa of the jellyfish, Cassiopea xamachana, starved 41 days in darkness, with 

 loss of about 96 per cent in weight. Lateral view, natural size. (After Mayer '14.) 



Fig. 14. — Same as Fig. 13, but magnified to original size, for comparison with Fig. 12, 

 to show more clearly the change in form undergone by the jellyfish Cassiopea during inanition. 

 Note the relatively small bell (umbrella) with upturned rim, and the relatively large arms with 

 rudimentary tentacles. 



In six weeks of inanition, with final loss of over 96 per cent in body weight, 

 there are likewise progressive changes in body form (Figs. 12, 13, 14). The 

 bell-rim becomes shrunken and bent upward, and the arms atrophic. The 

 mouths become closed by coalescence in about three weeks, so that subsequent 

 recovery by refeeding is impossible. The cells are reduced in size; many become 

 fused into a syncytial condition or degenerate and disappear. The gelatinous 

 substance, which forms about 95 per cent of the organism, is greatly reduced in 

 amount and becomes vacuolated. The commensal green algae become crowded 

 in the diminutive starving Cassiopea, and ordinarily most of them escape from 

 the body; but if the experiment is conducted in darkness most of the algae 

 degenerate, and die, although a few may persist and regenerate a new supply 

 upon refeeding. 



Hatai ('17) confirmed Mayer's formula for the loss in weight of starving 

 Cassiopea (after the first day), but found little change in the relative weights of 

 the mouth organs, umbrella and velar lobes. 



In connection with his experiments on partial inanition with various salt 

 deficiencies, Herbst ('97) made a few incidental observations on Cotylorhiza 

 tuberculata. Phosphorus was found necessary to enable the planulae to develop 



