100 



Papers from the Department of Marine Biology. 



of such a difference can not be doubted. We assume that this difference 

 in the nitrogen-content is due to the relative abundance of cellular 

 elements in the smaller individuals, contrasted with an excess of the 

 reserve materials composed of organic substances poorer in nitrogen 

 in the larger individuals. We thus find that, within the limits taken, 

 the reserve jelly-like substance and cellular elements probably both 

 have the same water-content, since otherwise the same percentage of 

 water throughout the series could not be expected. 



PERCENTAGE OF ASH IN SOLIDS. 



Since the percentage of water is similar in all the sizes of Cassiopea 

 examined, and since both cellular elements and reserve materials have 

 a like water-content, we should anticipate that the ash-content would 

 be also similar in the several stages, and the determination of the ash- 

 content on three individuals supports this conclusion. The proportion 

 of ash is as high as 52 per cent, thus making the organic substances less 

 than half of the entire solids. 



ANALYSIS OF DIFFERENT DIVISIONS OF THE BODY. 



Using four cassiopeas, which also appear in table 2, the three different 

 parts of the body were separately analyzed. The results are shown in 

 table 3. 



Table 3. — Water-content, solids, ami nitrogen in three different parts of the normal Cassiopea. 



