THE CCELOMTC FLU[D IN ACANTHODRTLTDS. 560 



3. Lamprocytes.^ — Large rounded cells with a distinct 

 pedicle ; Avitliout pseiidopodia. The cytoplasm is occupied 

 by numerous " vacuoles/' each of which usually contains 

 a small, highly refringent " granule." 



4. Linocytes.^ — Smaller clear cells, containing one or 

 more thread-like products. 



The relative proportions occupied by these four kinds of 

 cell varies; but the '"^ lamprocytes" are the most abundant, 

 and in a drop of fluid fill almost the entire field (fig. 1). The 

 "linocytes" are usually the fewest in number, but I have 

 evidence that they are more abundant in some worms than in 

 others ; but whether this is a seasonal or physiological or an 

 individual peculiarity I am at present unable to determine. 



The amcebocytes are only moderately numerous; and they 

 also vary in numbers. 



While in Octocheetus these cells remain distinct and 

 separate, those of Ac. annectens adhere together to form 

 clumps, so that when a drop of the fluid is placed on the 

 slide one sees what at first appear to be enormous cells, 

 visible to the naked eye. But examined under the micro- 

 scope — and especially after the use of iodine — these large 

 cells are seen to be groups of cells adhering closely to one 

 another. 



A variable number of cells occur in each group — usually 

 from six to twelve, but sometimes even more — and in each 

 group there is generally one linocyte, one or two eleocytes, 

 and the rest lamprocytes. 



1. Amcebocytes. — These appear under two forais, depend- 

 ing on the character of the granules and of the pseudopodia. 



The most usual form has a spherical, lather coarsely 

 granular body, with few, clear, filamentary pseudopods, 

 chiefly arisiug from one side (fig. 2). Whether or not this 

 form of pseudopods is the true and normal condition assumed 

 during the life of the cell iu the bod^' of the worm I am 



' XcifiTTpoc = shining, in reference to tlie highly refringent granules. 

 ^ \ivop = tliread. 



VOIi. 44^ PAKT 4, NKW SKKIES. 



