BULLETIN 39, UNITED STATES NATIONAL MUSEUM. [18] 



ZOANTHARIA. 



All the species of AntipatJies are fixed with saturated sublimate, and, 

 on account of the slight contractility of the polyps, their preparation 

 always succeeds. The saturated sublimate, which is used cold, should 

 be of the same volume as the water containing the animals. 



ACTINIARIA. 



The preparation of this group is very diflScult, the great contractility 

 and resistance of the muscular system of the majority of the species 

 frequently constituting insurmountable obstacles to success. Many 

 times when it is thought that the animal has been deprived of any sen- 

 sitiveness, immersion in a reagent of rapid action is sufficient to show 

 sudden and surprising contraction of the tentacles and of the whole 

 body. When several specimens of certain forms are treated with the 

 same method and under the same conditions, some die distended and 

 the rest contracted. Good results depend, in some cases, on circum- 

 stances which, up to the present time, are wholly unknown. After all, 

 however, there are many species with which perfect results can be 

 attained, if great care be exercised in the manipulations. 



Anemonia sulcata {Anthea cereus) is the easiest to prepare. When 

 well distended in running water, the animals are killed with the chrom- 

 picric solution, used in volume equal to that of the water in which they 

 are. This should be rapidly poured into the jar containing the Actinian, 

 after as much of the water therein has been x)Oured off as may be and 

 leave the animal immersed. A solution which is now ranch used instead 

 of the chrom-picric mixture just mentioned is made of — 



Chromic acid, of 1 per cent 1 part 



Saturated solution picric acid 1 part 



Formalin, of 4 per cent 1 part 



When the animals die, they will fall from the sides of the glass, and 

 they should then be transferred to another jar containing chromic acid 

 of one-half per cent, where they should be suspended upside down by 

 means of a glass float, the hook of which has been passed through the 

 lower rim of the body. The animals should be gently shaken to give 

 the tentacles a natural position. After half an hour they are placed in 

 weak alcohol, and then gradually transferred to that of 70 per cent. 

 It is a good plan to suspend the animals upside down by means of a 

 float in the final receptacle, though it is hardly worth while to do this 

 for the smaller specimens. 



The following Actinians may be killed with boiling saturated sub- 

 limate: Uloactis, Sagartia dohrni, Paranthus, Corynactis, and small 

 specimens of Aiptasia. Before they are transferred to alcohol, the 

 animals should be allowed to harden for some minutes in chromic acid 

 of one-half per cent. 



When Heliactis helUs, Bunodes gemmaceus, and B. rigidus are well dis- 

 tended, two-thirds of the sea water in the jar containing them should 

 be removed and its place filled by a chloral hydrate solution 0..} of 1 



