[27] THE PEESERVATION OF MARINE ANIMALS HOVEY. 



Gestus veneris.- — Have the auimal in a little water in the exhibition jar 

 and rapidly pour over it enough of chrom-acetic mixture Xo. 1 to fill the 

 jar three-quarters full, arranging the animal in a coil with the broad 

 edge on the bottom by means of a slender glass rod. After ten minutes 

 substitute chromic-acid solution for the chrom acetic, and after fifteen 

 minutes therein wash thoroughly in fresh water by decantation and 

 j)lace the animal iu 35 i)er cent alcohol. The gradual transfer to 70 

 per cent alcohol must take several days, and the jar must not stand 

 in direct sunlight or even strong diffused light. The specimens to be 

 treated should be in perfect condition; otherwise they will go to pieces 

 iu the fixing fluid. Cestus veneris can be well prepared in the chrom- 

 osmic mixture also, but many specimens are injured and colored too 

 much, whereas by the method just described they remain white and 

 nearly transparent. 



Vexillum may be treated like Gestus veneris. 



ECHINODEKMA. 



Grinoidea. — Antedon rosacea (Gomatula) is put directly into 70 per 

 cent alcohol, but A. phalangium, ou account of its tendency to break in 

 pieces of itself, must be killed in that of 90 x^er cent. tShake the vessel 

 violently to hasten death and prevent the animals from breaking off 

 their arms. When in doubt about the species use 90 per cent alcohol. 



The larval forms of the Pentacrinoids are narcotized with chloral 

 hydrate of O.l of 1 per cent — a process requiring two to four hours. If 

 they are then hardened in alcohol, they will remain with the arms per- 

 fectly distended. The more advanced stages are best killed with sat- 

 urated sublimate, where, however, they should remain only a few 

 moments to avoid injury to the membranes. 



Asteroidea. — To prepare the Stellarids with the ambulacral feet in a 

 state of distention, they are allowed to die in alcohol of 20 to 30 per 

 cent, being placed in the vessel ambulacra uppermost. 



Luidia. — Lay the animal ou its back in a shallow tray in barely 

 enough water to cover it. Then, wheu the ambulacral tentacles, which 

 are very long, are well distended, pour over it the chrom-acetic mixture 

 No. 2 and immediately transfer to 50 per cent alcohol and after two 

 hours remove to 70 per cent alcohol. Small individuals may be killed 

 with 55 per cent acetic acid, but greater care must be used to transfer 

 them to alcohol as soon as dead. 



Brisinga easily breaks oft' its arms, to avoid which it should be quickly 

 immersed in absolute alcohol. 



Bipinnaria makes excellent preparations when killed with the chrom- 

 acetic mixture ISTo. 1, and even better with the chrom-osmic mixture, in 

 which it should remain only a few minutes. Other larval forms are 

 treated with saturated sublimate solution. 



Some Ophiuroids are allowed to die in fresh water because they thus 

 remain distended and entire. Ophiothryx ecliinata is an examj^le. Cer- 

 tain small forms {Amphiura, Ophiactis) can be fixed directly in weak 



