232 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



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 

 (%• 23). 



There are numerous canaliform prolongations of the 

 ccelom, 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 'coelomic epithelium may be recognised, and 

 ccelomic corpuscles may be found in many of them. They 

 probably act as nutritive, and possibly also as excretory 

 and respiratory, channels. 



The coelomic fluid is a mixture of sea-water and 

 globulins (Krukenberg). Its specific gravity is on the 

 average 10288, but it varies somewhat according to 

 circumstances. It was found to be greater (1*0311) 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 1*0264. 



The fluid contains ccelomic 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 — '0i5 mm. long, which 

 are very numerous, and (2) smaller amoeboid, 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 amoeboid cells) become united to 

 form a clot. 



