AN OLIGOCHvETE WORM. 305 



take place, at least partly, by actual ingestion as well as by dif- 

 fusion of liquid nutriment. To try to prove this I have made 

 numerous experiments, but they were all unsuccessful. I kept 

 worms alive for a time in a weak solution of methylene-blue, 

 and then examined the cells of the gut to see if any of the 

 solid indigestible particles had been ingested by the cells, but 

 this was unsuccessful. I also tried feeding them on the scum 

 from a hay infusion, which contained numerous cysts, but this 

 was again unsuccessful. If the almost colourless material inside 

 the vacuoles is not actually ingested from the gut, I can only 

 think that it is some digestive liquid, formed by the epithelial 

 lining of the gut in these vacuoles, and then gradually forced into 

 the gut-cavity. This would mean that the vacuoles would be in 

 the nature of small digestive glands. Still, the fact that the cells 

 of the gut are so strongly ciliated, and the presence of these large 

 spaces in the wall of the gut filled with masses of almost colour- 

 less material, point at least to the possibility of nutrition being 

 partly by ingestion. 



Salivary Glands. — The salivary glands extend as far back as 

 the first pair of septal glands, which are situated in segment 4. 

 They enter the oesophagus just behind the pharyngeal ingrowth 

 (fig. 4). They are paired structures, each being a simple, undu- 

 lating, tubular gland. Transverse sections show that each gland 

 is of almost uniform thickness, ending in a slight swelling or 

 ampulla. Although these two simple tubular glands converge 

 towards the same point just behind the pharynx, they open into 

 the oesophagus quite separately on the dorsal side. 



The salivary glands have been called ^^ peptonephridia." The 

 main characters which distinguish these glands from nephridia 

 are (1) there is no opening to the coelom, (2) there is no trace 

 of a funnel, (3) the tubes are not ciliated, and in no Oligo- 

 chsetes are there nephridia which are entirely without cilia. 

 On the other hand, the segments occupied by the salivary glands 

 are devoid of other nephridia ; and Beddard (1, p. 47) found that 

 in Octochoitus multijiorus, the study of the development revealed 

 the fact that the "salivary glands" were undoubtedly formed by 

 the fusion of at least two "pairs of nephridia, which were at 

 first distinct and each provided with its own coelomic funnel which 

 is subsequently lost. This suggests that it is quite possible that 

 in the earlier stages of the development of Enchytrseids, the 

 " salivary glands " might have had an opening into the coelom, and 

 if so, this would do away with one of the chief arguments against 

 the nephridial nature of these " salivary glands." On the whole, 

 however, it seems best to leave the nephridial or non-nephridial 

 nature of the " salivary glands " an open question. 



Setce. — As before mentioned, the setae are straight with the 

 innermost ends curved like a hockey-stick. The setae are 

 slightly swollen in the middle (text-fig. 61 A). New bundles of 

 setse are constantly being formed by the side of the old ones. 

 Text-fig. 61 B shows three setse just beginning to be formed, and 



