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Percentage of Nitrogen in the Solids

mouth-organs and umbrella

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 former. 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 solids 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.