THE CCEfiOMIC FLUID IN ACANTHODRILI OS. 565 



The Coelomic Fluid in Acanthodrilids. 

 By 



W. Blaxlaiid Beiiliam, D.Sc, M.A., F.Z.S., 

 Professor of Biology in tlie University of Otago, New Zealand. 



With Plate 41. 



The corpusculated fluid contained in the coelom of Euro- 

 pean earthworms belonging to the family Lumbricidfe has 

 been the subject of a memoir by Dr. Rosa — from whose 

 careful studies we have learnt that, in certain species of the 

 genus Allolobophora, the corpuscles are of a varied 

 character — differing somewhat in different species ; and, 

 moreover, that the commonly accepted account of the 

 formed elements of the fluid is not only very incomplete, but 

 more or less erroneous. The usual description refers to this 

 fluid as " a colourless fluid with numerous amoeboid corpus- 

 cles." 'JMiis is an imperfect truth, for, in addition to 

 ^^amoebocytes," there are, in the commoner species of 

 Allolobophora, numerous "Eleocyte" cells containing 

 refringent oily globules, which are, however, absent in 

 species of the genus Lumbricus, where, it seems, their 

 place is taken by "vacuolated lymphocytes," which are not 

 endowed with amoeboid movement. 



Soon after my arrival in New Zealand, in 1898, I was 

 surprised to iiote, in the fluid of Octocluetus multiporus 

 Beddard — which served my students as the type of an 

 earthworm — not only very abundant cells, recalling the 

 eleocytes of Rosa, but curious " tiiread-coutaining cells," 

 similar to those then recently described by Goodrich as a 

 constituent of the coeloniic fluid of E iichy trte us h orteusis, 



