i897. NOTES AND COMMENTS. 299 



How ARE Crustacea to be Preserved ? 



These animals are still a difficulty. Dr. Haly " can find nothing 

 to supplant gum and glycerine for the preservation of their colours ; 

 they must not be placed in spirit before being placed Jn the solution, 

 nor must the solution be reduced by spirit. If they are touched by 

 spirit in any way the glycerine produces in a few hours great white 

 blotches on the carapace, causing a horribly leprous aspect. This 

 necessitates for large specimens the. use of a large quantity of the gum 

 and glycerine solution, which has then to be thrown away instead of 

 being used several times as is the case with fish ; the expense, there- 

 fore, becomes almost prohibitive. The effect of formol and carboliq 

 acid is the same as boiling water, and the chloride of zinc solutions 

 are most destructive. I am in hopes that solutions of gum in formol 

 may solve the question." 



We should be glad to receive communications on the above sub- 

 jects. No doubt the curators of some of our great museums, especially 

 the energetic Assistants in the Zoological Department of the British 

 Museum, have been experimenting on these Hues. It would be of 

 interest and value if they would detail the results of their investiga- 

 tions. 



The Fixation of Soft-bodied Marine Invertebrates. 



On this subject we have already published various notes, and the 

 present observations by Dr. Haly form a welcome addition. " Of 

 late years," he writes, " I have received recipes for the display of 

 marine animals by the Neapolitan methods, but I must confess that I 

 have never seen any sign of success with any of them. I imagine 

 that some practical training by a master of the art is necessary." 



" On the contrary, Thulberg's ' Solution of Chloride of Magnesium ' 

 promised well from the first, and I have been equally successful with 

 Epsom salts, which was suggested by some English naturalist for sea 

 anemones. No class of sea animals can resist the action of these 

 salts. The secret of their use is very simple : the salt must be dis- 

 solved in fresh water until the solution attains the specific gravity of 

 sea water ; this solution must then be mixed with from four to six 

 parts of sea water. All forms of marine life display themselves in 

 these mixtures to the utmost perfection. The difficulty is to transfer 

 them to the formol : some require no fixing, and, curious to say, 

 amongst them such delicate and excessively contractile forms as the 

 Tubicolar Annelids and the Gephyraeans. On the contrary, the 

 Holothurians and the Nudibranchiates are extremely difficult to pre- 

 serve in an extended state. Of the ordinary fixing agents, bi-chromate 

 of potash seems to answer better than any. I have also been suc- 

 cessful with excessively weak solutions of alcohol and by allowing 

 alcohol to float on the top of the water, and thus mixing with extreme 

 slowness. But I can give no recipe which works with certainty." 



