152 
region and in the tail, but in the middle portion of the 
animal it is uninterrupted by septa, although, as mentioned 
above, these are represented by certain thin bands which 
accompany the segmental blood-vessels across the coelom 
(fig. 23). 
There are numerous canaliform prolongations of the 
celom, best seen in sections of the anterior end of the 
animal, which penetrate into the musculature, or insinuate 
themselves between the brain and the _ prostomial 
epithelium, and often accompany the blood-vessels which 
supply the body wall. In most of the canals the thin 
lining of celomic epithelium may be recognised, and 
celomic corpuscles may be found in many of them. They 
probably act as nutritive, and possibly also as excretory 
and respiratory, channels. 
The ccelomic fluid is a mixture of sea-water and 
globulins (Krukenberg). Its specific gravity is on the 
average 1°0288, but it varies somewhat according to 
circumstances. It was found to be greater (1°0511) in 
worms which had been kept for thirty-six hours in moist 
sand and seaweed than in others which had been trans- 
ferred from the moist sand and seaweed to sea-water for 
three hours (1-0285), or over-night (1°0270). The specific 
gravity of the sea-water used was 10264. 
The fluid contains cclomic cells and, during a con- 
siderable portion of the year, reproductive products. The 
coelomic corpuscles (fig. 44) are abundant, and of two chief 
types—(1) fusiform cells about ‘04—05 mm. long, which 
are very numerous, and (2) smaller amceboid, or sub- 
spherical cells, many of which contain yellow or brown 
refringent granules. On exposure to the air a delicate 
fibrous network is formed, with which the fusiform cells 
(and to a less extent the ameboid cells) become united to 
form a clot. 
