104 



Papers from the Department of Marine Biology. 



Mayer (1914) found a simple law which governs the loss of weight in 

 starving cassiopea. The law is represented by the following formula 



Y = W{l-ay 



where Y represents body-weight W after x days of starvation, and 

 a stands for the constant that gives a fair measure of the rate of loss 

 of weight. Mayer calls this constant a the coefficient of negative 

 metabolism, since a increases as the loss of weight increases- 

 Extensive data given by Mayer show that this formula accords 

 satisfactorily with his observed data. The starved cassiopeas in my 

 hands showed, however, a sharp drop in the body-weight within 24 

 hours after commencing starvation ; thus the succeeding body- weights 

 were altogether too low as compared with the calculated values, when 

 this formula was applied. Assuming that the initial sudden loss in 

 weight was due to some peculiar conditions not understood at present 

 (possibly the escape of algae, etc.), I have taken the body-weight, 83.58 

 grams (see table 4), one day after starvation, as the starting-point, and 

 computed the successive losses of weight according to the formula^ 



y = 83.58 (1-0.05)^-1 



Table 5 shows the observed losses of body-weights (from table 4) 

 compared with those calculated by the revised formula. 



Table 5. 



By this modification the agreement between the observed and 

 calculated values becomes much more satisfactory. The somewhat 

 lower body-weight obtained in the present experiment as compared 

 with that calculated was probably due to the frequent handling of the 

 animal in order to determine the body-weight daily. The removal 

 of the adherent moisture with filter paper previous to weighing is 

 certainly severe treatment for the delicate medusan body. It is there- 

 fore rather a surprise to find that the formula, which has no additional 

 provision for the various experimental conditions except the two fac- 

 tors (number of days and initial body-weights) , can represent so closely 

 the data here obtained. 



^The discrepancy between my formula and that of Mayer is due to the fact that Mayer did 

 not commence his observations until after the cassiopeas had remained in aquaria in the laboratory 

 for one day (24 hours), and thus until after all undigested food had been discharged from the 

 medusa. The considerable loss during the first day is largely due to this fact, and also to the loss 

 of much slime soon after being captured. 



