begun to turn red as an effect of the acid, it should be removed 

 to the Kleinenberg solution, where it may remain fifteen minutes 

 before it is put into weak alcohol. 



Ctenophora 



Beroe ovata, Hormiphora, Callianira, Lampetia, Euchlora, 

 and young specimens of Cestus, Eucharis, and Bolina are killed 

 in the chrom-osmic mixture, in which they remain from fifteen to 

 sixty minutes, according to size, and are then transferred gradu- 

 ally to 70 per cent alcohol. 



While Beroe ovata is hardening in the alcohol, insert a 

 short glass tube of the proper size into its gastric cavity to 

 keep it distended in natural shape. Fix the tube so that it acts 

 like a float to keep the animal suspended in the liquid. This 

 operation must be effected with great care to avoid injuring the 

 longitudinal series of vibratile plates. After one or two days, 

 when the animal is in the 70 per cent alcohol, the tube may be 

 removed and the hardened animal will preserve its form. 



Beroe forskalii, to be preserved in a state of expansion, 

 must be immersed in the sulphate of copper and sublimate mixture, 

 and as soon as dead must be placed in the chrom-osmic mixture to 

 harden for an hour. Since this species is naturally flat, it is 

 not necessary to introduce a tube into it. 



Callianira may be treated like the last species, but another 

 good method is to kill it in a solution composed of — 



Concentrated pyroligneous acid 1 part. 



Saturated sublimate 2 parts . 



Chromic acid of one-half per cent 1 part 



Cestus veneris. — Have the animal in a little water in the 

 exhibition jar and rapidly pour over it enough of chrom-acetic 

 mixture No. 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 solu- 

 tion for the chrom-acetic, and after fifteen minutes therein wash 

 thoroughly in fresh water by decantation and place the animal in 

 35 per cent alcohol. The gradual transfer to 70 per cent alcohol 

 must take several days, and the jar must not stand in direct sun- 

 light or even strong diffused light. The specimens to be treated 

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

 in the fixing fluid. Cestus veneris can be well prepared in the 

 chrom-osmic mixture also, but many specimens are injured and color- 

 ed too much, whereas by the method just described they remain white 

 and nearly transparent. 



Vexillum may be treated like Cestus veneris. 



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