[23] THE PRESERVATION OF MARINE ANIMALS HOVEY. 



transferred to alcohol. Gunina is better wheu killed with concentrated 

 acetic acid before being hardened with the chrom-osmic mixture. A 

 simpler method for Carmarina is to use formalin of 4 per cent and 

 chromic acid in equal parts for killing and hardening. Allow the speci- 

 mens to remain in this mixture from one to two hours; then wash in 

 fresh water and transfer to alcohol. 



To prevent the flattening of the bell of Carmarina, Tima, and other 

 large forms place a watch glass in the bottom of the jar and rest the 

 bell of the hydrome lusa in its concave side. 



ACALEPH^. 



Charybdwa should be killed with the chrom- acetic mixture Ko. 2 and 

 immediately afterwards treated with chromic acid of one-half of 1 per 

 cent. After a half hour transfer to alcohol, taking care for the proper 

 suspension of the tentacles. 



NausUhoe, the ephyra of Pelagia, and BMzostoma are killed by pour- 

 ing into the sea water containing them 3 per cent of a 1 per cent solu- 

 tion of osmic acid. When they have just begun to take on a brown 

 tint they should be washed in fresh water and placed in 35 per cent 

 alcohol. Formalin of 4 per cent may be used with excellent results 

 with these animals, because it does not give the brown tint which is 

 imparted by osmic acid. To avoid the flattening of the umbrella of 

 Rhigostoma, the animal is killed in an exhibition jar with a somewhat 

 narrow neck. After the transfer to weak alcohol the mouth of the jar 

 should be covered with a piece of bladder and should stand upside 

 down, with the convex part of the bell resting in the neck. The medusa 

 should remain in this position until the alcohol has been changed to 70 

 per cent and the whole body has become permeated with the fluid. 

 When formalin is used for killing and hardening, this inverted position 

 should be maintained from the first. 



Pelagia noctiluca should remain in the chrom-osmic liquid about an 

 hour, and then be washed and placed in weak alcohol. In the alcohol 

 the animal should be suspended by threads tied carefully to the 

 extremity of each tentacle without tearing it. See that the bell does 

 not touch the bottom of the jar and let the animal remain thus only 

 until completely hardened. 



Cotylorhiza tuherculata {Cassiopeia). — Formalin of from 2 to 3 per 

 cent may be used to good advantage for killing and hardening this 

 species. Another method is to treat with osmic acid, as was done with 

 Phizostoma, but when the brown tint begins to appear, a 5 per cent 

 solution of bichromate of potassium should be substituted for the osmic 

 acid and should be renewed after a few days. The animal ought to 

 remain in this reagent for about two weeks, but it can not remain much 

 longer than that without suffering injury. Then remove the object to 

 35 per cent alcohol. Numerous crystals of a salt are formed on the 

 outside of the animal and a heavy precipitate falls to the bottom of the 



