382 PRESERVATION OF MARINE ORGANISMS 



in chains. Pour a large quantity of the mixture into 

 the vessel containing the Salps. Wash well in water 

 before transferring to alcohol or formalin. 



Doliolum and other very small Salps may be killed 

 by dropping them into picric acid, but simple formalin 

 acts very well. 



Fishes. — The best preservatives for fishes are — 

 (i) Five per cent, formalin (say 2 per cent, formalde- 

 hyde) ; (2) 70 per cent, alcohol ; and (3) 70 per cent, 

 alcohol to which 5 per cent, formalin has been added. 



For preserving for a short time only there is little 

 doubt that 5 per cent, formalin is the best, as both the 

 form and colour are better retained. After a con- 

 siderable time, however, the specimens deteriorate. 



Holt and Byrne recommend preserving first in 5 per 

 cent, formalin (40 per cent, strength), and then trans- 

 ferring to alcohol, or after a few weeks to equal parts 

 95 per cent, alcohol and formalin 5 per cent. 



Fish intended specially for dissection are best pre- 

 served in formol-alcohol. 



The best way of preserving the colours of fish is to 

 preserve in 5 per cent, formalin, and keep the specimens 

 in the dark. But even under these conditions the 

 colours last a few months only. 



Fish Eggs and Larvae. — These are best preserved in 

 5 per cent, formalin. They retain both form and size 

 well in this fluid, whereas in alcohol they shrink con- 

 siderably. 



