[29] THE PRESERVATION OF MARINE ANIMALS HOVEY. 



H. inipatiens, wliich has a long, soft body, is to be seized by the neck, 

 so that the tentacles can not contract, and by the i)Osterior extremity, 

 so that the body may not shorten, and in this manner the whole 

 animal is immersed in concentrated acetic acid. When dead it is trans- 

 ferred at once to alcohol, without making an injection. 



Thyone, Thyonidium, and PJiyllophorus are strangled without using 

 much force, wholly immersed in acetic acid, and then removed to alco- 

 hol as soon as dead. If the individuals aie very small, the pressure 

 on the neck should be made with forceps instead of the fingers. 



Cucumaria plancii is treated like the large Holothurians, except that 

 the injection of alcohol is made through the mouth, taking care to keep 

 the tentacles distended, and it is not necessary to close the opening 

 with a cork. The other species of Cucumaria are Killed in the same 

 manner. It is not necessary to inject the small specimens. 



The large Synapta, in the preparation of which much difficulty has 

 been experienced on account of its tendency to break to pieces, is killed 

 by immersion in a tube containing sea water and ether in equal parts. 

 In this mixture the animals usually die completely distended. When 

 dead and well distended, they are washed in fresh water and put 

 into weak alcohol. The transfer to 70 per cent alcohol should be very 

 gradual, to avoid contraction. Chloroform may be used instead of 

 ether. The hardening may also be done by putting 2 or 3 c. c. of 1 per 

 cent chromic acid into the water in which they have been washed. 

 After a few seconds remove to weak alcohol. 



The rare Molpadia musculus and the little Ghirodota venusta have 

 been also prepared by this method. Auricularia is best killed in the 

 mixture of sulphate of copper and sublimate or in sublimate alone. 



ENTEROPNEUSTA. 



Balanoglossus is killed with the Kleinenberg solution or in chromic 

 acid of one-half of 1 per cent, but the former is much better. When nar- 

 cotized in alcoholized sea water the animals remain well distended and 

 straight. Tornaria is killed with the sulphate of copper and sublimate 

 mixture. It is well preserved also with saturated sublimate or with 

 the chrom-osmic mixture. 



The Cestodes are fixed with cold saturated sublimate, the Trematodes 

 with the same solution hot. If it is desired to have flat preparations 

 to mount for the microscope, the animals should be placed between two 

 plates of glass, which are brought together by gradual pressure, and 

 then placed in a crystallizing dish under moderate weights. When the 

 animals are flattened enough and there is as little water as is practica- 

 ble in the dish, pour over them boiling saturated sublimate and leave 

 them therein until they show no signs of contraction. Then, the plates 

 of glass being removed, the worms are allowed to harden thoroughly 

 in cold saturated sublimate, since the boiling sublimate fixes only the 



