DEPARTMENT OF MARINE BIOLOGY. 



181 



which are not found at Tortugas. It is the hope of the writer to obtain in 

 the future a sufficient number of the small snappers for the completion of this 

 investigation. 



In this preliminary report I shall present merely the average of the brain 

 weights in order^to indicate their magnitude for fishes of different sizes. 



Mean iveights of the fresh brain in the gray snapper, Neomoenis griseus, 

 according to body-length.^ 



^Body-length = Tip of snout to middle of tail. 



I have also determined the brain-weights of several other kinds of fishes, 

 but the data so far obtained are too scattered to justify their publication at 

 this moment. 



Changes in the Composition of Cassiopea xamachana during various periods 



of Starvation, by S. Hatai. 



In my previous work on the changes in the composition of Cassiopea xama- 

 chana (1917) it was found that at the end of 25 days of starvation the absolute 

 amount of nitrogen in the starved Cassiopea was considerably higher than in 

 normal specimens having the same body-weight. It was noted also that, 

 although high when compared with a normal specimen equal in weight to the 

 starved animal, it was very low for the initial body-weight of the starved 

 animal. From this it was inferred that the nitrogen had also been consumed 

 during the period of starvation. 



Since the above conclusion was reached by comparing two different series 

 of individuals, one starved and other not starved, and since the two series 

 might possibly be dissimilar in respect to their nitrogen content, it was 

 thought desirable to modify the experiments by starving one half of each 

 specimen, while the other half was utilized for control. We hoped thus to 

 avoid a possible error which might arise from individual peculiarities. Further- 

 more, it was the object of the present experiment to determine the changes in 

 the composition during various stages of the starvation, since in this way we 

 might obtain a much clearer notion of the rate of nitrogen change accompany- 

 ing the different rates of reduction in the body-weight. 



All together 15 cassiopeas were taken. These were divided into 5 groups, 

 each group containing 3 individuals, and were starved for various periods — 

 3, 7, 14, 21, and 25 days. In each case, one half of the medusa was subjected 

 to stai^vation, while the other half was examined at the beginning of the 

 experiment. The mode of the starvation was similar to that in the previous 

 study — that is, the sea-water was doubly filtered to remove all trace of the 

 micro-organisms, and the medusa which was to be starved was kept in such 

 water. The water was changed once a day throughout the period of starva- 

 tion. The test animals were weighed but twice, at the beginning and at the 



