JELLY-FISH 373 



success. At the right moment formalin is poured in to 

 kill. The success depends upon adding the formalin 

 just at that moment. 



The Cystonectae (Physalia, etc.) are quickly killed 

 with a mixture of corrosive sublimate and acetic acid. 

 Transfer to chromic acid \ per cent, for about an hour, 

 and then remove to dilute alcohol, and gradually 

 increase the strength to 70 per cent. Care must be 

 taken not to touch a living Physalia, as its stinging 

 power is tremendous, and the pain is excruciating. 



The Disconectae (Vetella, Porpita, etc.) are fairly 

 easy to preserve. Velella may be killed with picric 

 acid or corrosive sublimate. Add, after death, a little 

 chromic acid for hardening the tissues. Leave the 

 specimen for about half an hour in the mixture, and 

 then transfer to dilute alcohol after picric, but after 

 corrosive wash well in water and then put into 

 alcohol. Velella frequently dies fairly well expanded 

 in formalin. Porpita is best killed with picric acid ; 

 transfer to alcohol or formalin. 



Scyphomedusae are quickly killed with formalin. 

 Make up a solution of about 5 per cent, formalin by 

 pouring some strong formalin into sea water. Select 

 a vessel a little larger than the specimen, pour in the 

 formalin solution, and place the specimen in, mouth 

 upwards. Leave it alone for about an hour, and then 

 add a little strong formalin and give a gentle stir up. 

 It must not be forgotten that Scyphomedusae contain 

 an enormous amount of watery fluid, hence the neces- 

 sity for adding strong formalin to keep up the strength 

 of the solution, which should be at least 10 per cent., 

 before storing away the specimen. In the case of large 

 Scyphomedusae it is best to give small doses of strong 

 formalin at intervals of about two or three days, and 

 to give a thorough stir up, moving the specimens about. 



