REPORT ON CORALS—HYDROCORALLIN . 17 
Professor Claus’ Grundziige der Zoologie, 3" Auflage, 1874, p. 226, rightly placed the 
Milleporidze with the Hydroids. 
General Nelson’s figures (published by Professor Martin Duncan") of the animals 
of Millepora alcicornis do not seem to be of very much value. They appear to represent 
imperfect conceptions of the dactylozooids. In September 1878 Mr William North 
Rice published a short aecount of his observations of the living polyps of Muillepora 
alcicornis at Bermuda. He saw apparently only the dactylozooids, of which he gives 
outline figures. The tentacles are not disposed in them in whorls of four as figured by 
General Nelson, but more as in Millepora nodosa as described by me. His results go to 
confirm my own in several points of importance.” 
Meruops EMPLOYED. 
Sections of the corallum were prepared in the usual manner by grinding. Portions 
of the living coral were placed in various solutions for subsequent examination, viz., in 
absolute alcohol, chromic acid, and glycerine. Portions were further treated with osmic 
acid, and then transferred to glycerine or absolute alcohol. Fragments of the hardened 
coral were subsequently decalcified with hydrochloric acid, and the residual soft struc- 
tures were either mounted entire for examination, or cut in the usual manner into fine 
vertical and horizontal sections. The sections were stained with carmine or magenta. 
The specimens hardened in osmie acid, and decalcified after subsequent immersion in 
absolute alcohol, yielded the best histological results. Those which had been hardened 
in absolute alcohol alone gave the best results as to the coarser anatomy. The specimens 
preserved directly in glycerine preserved most perfectly the forms of the several histo- 
logical elements, and especially yielded good preparations of the thread-cells, preparations 
of which are best procured by grinding up between two glass slides a zooid and its 
immediately surrounding calcareous bed, removed with the point of a scalpel. A view of 
the structure unacted upon by acids is thus obtained. The specimens placed in chromic 
acid were of little service for sections, owing to a thick crystalline deposit of sulphate of 
lime which formed upon them in the solution ; but they showed best, on the under 
surface of the decalcified superficial film, the ramifications of the soft parts of the 
hydrophyton. Dr G. von Koch’s’ method of cutting sections of corals in which both the 
hard and soft parts are displayed in the same preparation will no doubt yield excellent 
results in the case of the Hydrocoralline. 
1 Ann. and Mag, Nat. Hist., vol, xvii. p. 354. 
2 Wm. North Rice On the Animal of Millepora alcicornis, American Journ. of Science and Art, vol. xvi., Sept. 
1878, p. 180. 
3 For an account of the method, see Zool. Anzeiger, Bd. i. 
(ZOOL, CHALL, EXP.—PART vil.—1880.) G3 
