THE ANATOMY. BLOOD-GLANDS 



79 



Fig. 34. ' 



is perhaps the homologue of the perientcric vessel of its segment, is largely filled by 

 a mass of big vesicular cells containing granules. They are so numerous as to nearly 

 occlude the lumen of the blood-vessel. 



The last variety of these organs are possibly the modified calciferous glands of 

 certain genera of Eudrilidae, for instance StuMmannia. I have, however, described 

 these in full under the description of the calciferous glands, and need not recur to 

 the matter here. 



The nature of these various glands now requires consideration. There can, I think, 

 be no morphological comparison between the organs in Perichaeta and those of the 

 Lumbriculidae, on the one hand, with the other varieties of blood-glands ; nor is 

 there any relation except perhaps a physio- 

 logical one between the blood-glands of the 

 two genera of worms mentioned: the other 

 organs do appear to me to be probably mor- 

 phologically connected. There is no doubt, 

 I imagine, that the peculiar glands of certain 

 Eudrilidae which I have described above 

 are really the equivalents of the calciferous 

 glands ; their lumen, although much reduced, 

 communicates with that of the oesophagus ; 

 and the segments which they occupy are those 

 in which calciferous glands, when present, commonly lie. At the same time it appears 

 to be at least probable that their function is a different one from that possessed by 

 the calciferous glands ; I could find no evidence of a secretion of calcareous particles ; 

 this merely negative evidence is not perhaps very strong, since I have often failed 

 to discover any such particles in the lumina of glands which are undoubtedly calciferous 

 glands. It is the structure which leads to the inference that the glands now under 

 consideration are not functionally calciferous glands; this is most clearly marked in 

 Eiulriloides, and the structure in that genus offers a clue to what is the real function 

 of the glands in question. The peculiar cells which make up the mass of the glands 

 become altered in Eudriloides towards the periphery of the glands ; it gets to have 

 a distinctly columnar arrangement ; but the columns of cells are disposed round a 

 lumen which is filled with blood and which is a blood-vessel traceable into connexion 

 with the other blood-vessels of the gland and the surrounding organs ; the structure 

 seems to be irreconcileable with any other theory than that the glands in question 

 have some secreting function in relation to the blood or eliminate effete matters 

 from the blood ; we have in fact a gland originally performing a function connected 



PEKICHAETA : BLOOD GLANDS. 



i. Dilatation upon blood-vessel filled with corpuscles. 

 2. Small blood-vessel. 



