THE CCELOMIO FLUID IN ACANTHODEILIDS. 575 



I am, however, unable to say which of the two cells is 

 derived, or which is the earlier stage in the history. 



In Ac. annectens these lamprocytes contain much 

 larger "granules/' about twice the size of those in Octo- 

 chfetus; they have a much higher refringency, and are so 

 abundant that, when viewed by transmitted light, the whole 

 cell appears opaque and nearly black. The granule nearly 

 fills the vacuole. 



Actions of Reagents. — Stains. — Gentian violet, in the 

 fresh, stains the nucleus deep violet : the cell membrane is 

 also stained, though less so than the nucleus. The cytoplasm 

 is scarcely tinted, while the vacuoles become a very pale 

 violet, so that in a glycerine mount they show up very dis- 

 tinctly. 



Iodine. — The cytoplasm is stained only a very faint yellow 

 — quite different from the brown colour exhibited by the 

 eleocyte. The " vacuoles " also share in this yellow colora- 

 tion, as is best seen in those isolated and freed from the 

 cytoplasm, but the granules remain uncoloured. 



Acids, Alkalies, etc. — When treated with nitric acid 

 the "vacuoles" burst after swelling; the granules are thus 

 released, but soon dissolve, accompanied by a good deal of 

 turmoil in the cell. Though I could not detect any actual 

 bubbles, yet the cell-contents seemed to be "on the boil," 

 as Goodrich has expressed it in regard to the action of 

 certain reagents on cells of Vermiculus. 



Hydrochloric and sulphuric acids have the same effect. 



Acetic acid (glacial) dissolves the granules after first 

 causing the " vacuoles " to swell and disappear. The 

 granules are insoluble in oxalic acid. 



In potash the entire cell swells, and the contents disappear 

 instantaneously on the arrival of the reagent. 



Neither absolute alcohol nor ether dissolve the granules. 



4. Linocytes. — These thread-containing cells are, with- 

 out doubt, the most interesting and puzzling of the cell- 

 constituents of the fluid, and, though bearing some resem- 



