REPORT ON CORALS — HYDROCORALLIN^. 35 



Methods Employed. 



The methods employed in investigating the structure of the Stylasteridse were mostly 

 similar to those made use of in the case of Millepora. 



A brief examination of some of the soft structures of certain of the Stylasteridse 

 was made while they were in the fresh condition, and especially of the various ele- 

 ments of Sporadopora dichotoma and of the female gonophores of Cryptohelia ; but 

 since the trawl-net by which most of the specimens available for examination were 

 obtained came up late in the day, very little, unfortunately, was able to be done in 

 this way. 



Portions of the corals were preserved by means of chromic acid, osmic acid, absolute 

 alcohol, and glycerine, and they were subsequently decalcified and examined in the 

 usual manner by means of sections. In cutting the sections, a method described by 

 Milchalkovics, Arch, fur mikroskopische Anatomie, ii. Bd. 3 tes Hft., p. 386, was adopted 

 and found to yield most successful results. The method is especially valuable for cutting 

 fine sections of structures, the parts of which are loosely held together, and where it is 

 desirable to maintain the exact relations in position of parts which in the sections other- 

 wise become entirely disconnected from one another. A strong jelly composed of equal 

 parts of glycerine and gelatine is used as an imbedding substance. It permeates the 

 tissues and takes the place of the hard calcareous supporting structures which have been 

 removed by the acid. The sections are mounted in glycerine, and the imbedding 

 substance which is left in situ in the sections becomes perfectly transparent ; in fact, 

 almost invisible in this fluid. No doubt Dr von Koch's method referred to above will 

 yield valuable results in the future. 



Structure op the Hard and Soft Parts in the several Genera of the 



Stylasteridse. 



I now proceed to a detailed description of the structure of the several genera of the 

 Stylasteridaa. 



Each of the members of the family is composed of hard inert calcareous parts, or 

 ccenosteum, and soft living structures. In the case of each genus the structure of the hard 

 parts will be first treated of, and then that of the soft parts. The latter consists of 

 ccenosarc, zooids, and gonophores, and will be described under these several headings in 

 each case. A full description of all details will be given in the case of Sporadopora, 

 which will be first accounted for, and in the cases of the other genera only those jjoints 

 in which they differ from it will be dwelt upon. 



