THE ANATOMY. NEPHRIDIA 47 



have since been described in the Acanthodrilidae, Eudrilidae, Cryptodrilidae, and 

 Geoscolicidae. 



In the Enchytraeidae they are the so-called salivary glands, which have been 

 described by VEJDOVSKY, MICHAELSEN, and others ; in certain species of this family 

 there are a pair of tubes which are more or less branched, opening into the alimentary 

 canal behind the pharynx ; sometimes the apertures are lateral in position, sometimes 

 they are dorsal and ventral respectively. The principal reason for considering these 

 tubes to be of nephridial nature is their minute structure ; they have a lumen which 

 is undoubtedly intracellular ; it is, however, necessary to be careful not to bo too 

 much influenced by a consideration of this nature ; the calciferous glands, for 

 example, are in some worms folded in so complicated a fashion that the lumen 

 becomes intracellular ; the lumen of the blood-vessels is also intracellular ; it has 

 been shown that minute vessels are formed by the canaliculisatiou of cells (by 

 LANKESTEB in the Leech). The salivary glands of the Enchytraeidae, however, 

 differ from nephridia in having no opening into the coelom ; there is not the least 

 trace of a funnel. Perhaps this fact is not of first rate importance as an argument 

 against their nephridial nature ; but it must be considered. Moreover the tubes are 

 not ciliated ; this again is against any homology with nephridia ; in no Oligochaetous 

 worm are there nephridia which are entirely without cilia ; it frequently happens 

 that a greater or less section of the nephridia is devoid of cilia ; but the non-ciliated 

 area is restricted. The segments which are occupied by these salivary glands are 

 devoid of other nephridia ; this, at first sight, suggests the metamorphosis of the 

 missing nephridia into the salivary glands ; but it must be remembered that in the 

 Enchytraeidae, as in most other of the lower Oligochaeta, the nephridia are defective 

 in the anterior segments of the adult worm. On the whole, it seems that the 

 nephridial or non-nephridial nature of the salivary glands of the Enchytraeidae must 

 be left an open question. It is quite otherwise with those earthworms in which 

 similar salivary glands occur. The first description of nephridia opening into the 

 anterior part of the alimentary canal in an earthworm was by myself in Octochaetus 

 multiporus; in this worm there are lying along the pharynx a pair of tufted organs 

 which end in a duct of some dimensions ; this duct runs forward and opens into 

 the buccal cavity ; here again one objection to the nephridial nature of these glands 

 is the fact that they do not appear to be furnished with any coelomic pore. This 

 statement, however, only applies to the glands in the adult worm. Fortunately in 

 this particular instance the development has been traced and I have found that 

 these compact glands are really formed by the fusion of at least two pairs of nephridia 

 which are at first distinct and each provided with its own coelomic funnel. There 



