112 F. W. GAMBLE, M.SC., AND J. H. ASHWORTH, B.SC. 



undergo remarkable changes in certain parts of the body, resulting in 

 the formation of (1) chlorogogenous tissue, (2) ova or spermatozoa, (3) 

 coelomic corpuscles. 



The coelomic fluid is a mixture of sea-water and globulins, among 

 which only paraglobulin has hitherto been detected (Krukenberg, 1882, 

 p. 87). We find that the specific gravity of the fresh fluid (including 

 corpuscles) varies slightly, but is on the average i'0288. 1 



On exposure to air this fluid coagulates, and a delicate fibrous net- 

 work is formed, binding the corpuscles together. If carmine is injected 

 into the ccelom, it is removed by the coelomic corpuscles, by the cells 

 lining the ccelom and by the nephridia, and there is no trace of carmine 

 in the coelom after forty-eight hours. 2 



Coelomic Corjmscles. — These abundant cells occur in two chief forms, 

 which probably pass into one another. The first varies from 8 to 20 fx 

 in length, is amoeboid, and usually contains yellow or brown granules 

 of a very highly refractive character. The pseudopodia are often 

 grouped at the two ends of the cell (PI. X., Fig. 24). The longer forms 

 of this kind of corpuscle pass into the second or spindle-shaped cells of 

 the coelom, which measure as much as 50 /j. in length, and contain no 

 coloured granules. These fusiform elements are most abundant, and 

 constitute the most characteristic features of the coelomic contents. 



The chlorogogenous tissue of the ventral vessel and its branches in the 

 body-wall consist of groups of cells about 20 ^ in length, full of large 

 slightly yellow or deep brown granules, which are not highly refrac- 

 tive. The tissue in old black worms is immensely developed, so as to 

 completely cover the vessel by the masses of hair-like threads, each 

 thread consisting of a small blind diverticulum of the vessel surrounded 

 by the chlorogogenous cells. 



11. Reproductive Obgans. 



Thanks to the researches of Cosmovici (1880), Cunningham (1887), 

 Kyle (1896), and others, the true ovaries and testes of Arenicola marina 

 are now known to arise by proliferation of the peritoneal covering of an 



1 It was found to be least ( 1*0270) in specimens which had been kepi for 

 some time in sea water, and greatest (1 "0311) in those which had been kept 

 for thirty-six hours in moist seaweed only. The specific gravity of the sea 

 water used was 1 0264. 



2 Schneider, 'Arbeit. Naturf. Gesellschaft,' St. Petersburg, Bd. xxvii, 

 Heft 1, 1890. 



