372 PRESERVATION OF MARINE ORGANISMS 



Siphonophores.— The belled forms (Calve onectae) are 

 about the easiest siphonophores to preserve, and for 

 them formalin is recommended. The stolon bearing 

 the cormidia usually becomes contracted, but occa- 

 sionally one is killed in an expanded condition. A 

 sudden dose of picric acid is a good killing agent, as 

 it acts very quickly. Leave the specimens in the 

 picric for about twenty minutes, and then gradually 

 transfer to formalin or alcohol. 



The forms with a small float (Physonectse) require 

 a considerable amount of skill, patience, and ex- 

 perience for their successful preservation in an ex- 

 panded condition. Unless one is prepared to devote 

 the necessary time and attention to the operation, it 

 is far better to place the colonies of these and the other 

 groups in formalin 5 per cent, or 10 per cent., and 

 chance the result. When dismemberment of the 

 colony takes place, collect the fragments and put them 

 all into a small bottle. 



For killing colonies in an expanded condition a 

 mixture of corrosive sublimate and copper sulphate 

 is frequently used. After the death of the colony, a 

 few drops of nitric acid are added to prevent the 

 formation of precipitates. Then Flemming's solution 

 is poured in for the purpose of hardening the tissues. 

 After about twenty-four hours in the above mixture 

 alcohol is introduced, just a few drops at a time, and 

 the strength very slowly and gradually increased to 

 70 per cent. Nearly all the methods for the preserva- 

 tion of Siphonophora were published before the advent 

 of formalin, and alcohol is always recommended. 

 Formalin, however, has several advantages over alcohol 

 for these delicate organisms, and should always be 

 given a good trial. 



Menthol has been used as an anaesthetic with some 



