On the Composition of Cassiopea Xamachana. 101 



PERCENTAGE OF WATER. 



It will be seen that the percentage of water in these three different 

 parts of the body is nearly the same. The water-content of the 

 umbrella is, however, constantly higher by about 0.7 per cent as con- 

 trasted with the two remaining parts. This is interpreted as probably 

 due to the inclusion in the umbrella of the contents of the stomach, 

 which are mainly liquid. The fact that the velar lobes (which have a 

 large proportion of cellular elements) and the mouth-organs (which 

 have a large proportion of reserve jelly-like substance) are practically 

 identical in water-content shows not only the same degree of water 

 inhibition in both cells and reserve substance, but also an equal dis- 

 tribution of salts. 



PERCENTAGE OF NITROGEN IN THE SOLIDS. 



Despite the fact of the uniform distribution of water and probably 

 of salts in the body, the nitrogen-contents of these three parts are 

 different. Table 3 shows that the nitrogen-content is highest in the 

 velar lobes, where the cellular elements are most abundant, while it 

 decreases in the mouth-organs and umbrella in the order named. 

 The higher nitrogen-content in the mouth-organs, as compared with 

 the umbrella, is assumed to be due to the relatively greater abundance 

 of the cellular elements in the fonner. We can infer from these data 

 that the ground substance, or the reserve jelly-like substance, must be 

 composed of organic materials poor in nitrogen. I shall discuss this 

 point later in connection with the probable chemical nature of the 

 reserve material. 



The observations made on the normal cassiopea may be sum- 

 marized as follows: 



(1) Relative weights of mouth-organs, umbrella, and velar lobes differ some- 



what according to the size of the entire body. 



(2) The water-content of the entire body, as well as of different parts, is 



practically identical throughout the animal's life cycle, so far as 

 followed. 



(3) The percentage of nitrogen in the soUds is highest in the smallest medusa 



and the values decrease progressively with increasing body-weight. 

 The percentage of nitrogen is highest in the velar lobes and decreases 

 in the mouth-organs and umbrella in the order named. All these 

 observations are interpreted as indicating that in the structures in 

 which the cellular elements are abundant the nitrogen-content tends 

 to be high. 



(4) The ash-content, like the water-content, is probably the same not only in 



the cassiopea as a whole, but also in each of the three parts through- 

 out the life cycle. 



