Royal Physical Society. 465 



anything like a natural appearance. I cannot, be it under- 

 stood, assert that I have yet succeeded in procuring an anti- 

 septic fluid which combines all the properties such a solution 

 should possess, — i.e., to preserve perfectly, form, consistency, 

 and colour, — but I believe I am fully justified in stating, that 

 I have been able to make a step in that direction. 



My experiments were first made with pure Glycerine, and 

 I found that with it I could preserve the colour of star-fishes 

 (as had been already done by others), and also that the smaller 

 Medusas preserved their forms in it. The Actinim were also 

 tolerably preserved, so far as colour was concerned ; but with 

 large Medusas it was a total failure. The chief objection to 

 the use of Glycerine is the undue transparency it communi- 

 cates to zoological specimens ; another is the slimy unsub- 

 stantial consistence it generally imparts. 



There are unfortunately two other barriers to its extensive 

 use, — i.e., the high price it commands, and the difficulty of 

 getting it pure. 



I made the attempt to dilute the Glycerine with a fourth, a 

 third, and a half of its bulk of water, and, as a result, lost 

 my specimens. 



Acetic Acid, I tried for Medusas, but found that, however 

 diluted with water, the specimens always shrank and became 

 opaque in it. 



White Arsenic was equally unsuccessful when used for star- 

 fishes, the specimens invariably loosing colour, and ultimately 

 decaying. 



Chloride of Zinc and other metallic salts did not give satis- 

 factory results, as they almost invariably caused the specimen to 

 shrivel and assume the consistency of a piece of hard leather. 



Goadby's solution for Medusce (in Forbes' " Medusas," Vol. 

 of Ray Society) I found to answer very well, but with the 

 great objection, that it finds so many ways of exit from the 

 preparation jar, and crystalizes so quickly, that a moderately 

 sized collection put up in that fluid would require to have a 

 man towel-in-hand, watching it from morning till night. 



The fluid I would propose for the preservation of Medusae, 

 while it is free from this objection, preserves, I think, the 



