THE MEDUSA. 169 



Specimens must not be left long in any solution contaiaing cocaine, as it has a softening 

 action, causing the umbrella to lose its firmness and to become very limp. 



When only one or two specimens have to be preserved a large watch-glass or a small 

 glass pot had better be used. Place in it the specimen with just suificient sea-water to 

 cover, add two or three drops of cocaine. As soon as it is anaesthetized pour the 

 formalin or the fixing reagent quickly upon the specimen. 



Formalin and Chromic Acid for ScyphomedustB. — Small Scyphomedusse die fairly well 

 expanded when simply placed in formalin 10 per cent, in sea-water. Tiie addition, after 

 the medusa is dead, of chromic acid is a distinct advantage. The chromic acid acts 

 upon the jelly and makes it tougher and more pliable. The yellowish-brown colour of 

 the chromic acid may be disregarded, as it gradually turns to a pale bluish-green 

 by oxidation. The strength of the chromic acid may be either 5 or 10 per cent., the 

 exact percentage is of little importance ; just pour in enough to colour the formalin. 

 The mixture I use contains roughly about one volume of chromic acid 5 per cent, 

 solution, and nine volumes of formalin 10 per cent, solution. 



After the specimen has been soaking several days in the chromic-formalin solution, 

 into which a little strong formaldeliyde must be daily poured and well stirred up, it 

 should be transferred, without washing, to a fresh 10 per cent, solution of formalin, and 

 then the bottle may be sealed and stored away. If, however, a few months later it 

 should be noticed that the formalin is becoming cloudy and milky, it means that 

 maceration is going on, and that an iusufFicient quantity of formalin was used. The 

 bottle should at once be opened, the fluid poured ofi", and a fresh solution of formalin 

 added. 



The successful preservation of Scyphomedusaj, especially the large ones, greatly 

 depends upon using plenty of strong formalin, so that the animal may become thoroughly 

 saturated. It must be remembered that a jelly-fish contains an enormous quantity of 

 fluid, all of which has to be replaced by the formalin solution. Hence the necessity of 

 keeping up the strength of the solution and the stirring. 



Damage done by Air-Bubbles in Tabes and Bottles. — Although great care is some- 

 times taken in preserving medusje, yet no care is taken in properly storing the specimens 

 for travelling. I have frequently opened tubes and bottles containing specimens in an 

 excellent state of preservation, but broken in fragments. The damage has been done 

 after the specimens went into the bottle, and not by the tow-net. There is nothing 

 more disastrous to delicate animals, like medusae, than an air-bubble rolling about in a 

 narrow tube, or a large air-space in a bottle which is subject to the rolling of a ship or 

 the shaking in a railway-train. Bottles with large hollow glass-stoppers are frequently 

 responsible for the destruction of specimens ; such stoppers should be plugged-up with 

 paraffin-wax. If tubes are being used a plug of cotton-wool should be placed in. After 

 the specimens are in the tube, fill it to the brim with formalin, and then push in a tight- 

 fitting plug of cotton-Avool, which has been previously saturated with formalin, taking 

 care not to introduce an air-bubble. The tubes can either be stored in a large jar of 

 formalin, or corked and sealed with paraffin-wax. 



When bottles are used, the common 1 oz. to !■ oz. sizes, with the best corks, are most 



29* 



