THE VICTORIAN NATURALIST. 77 



not be acted upon by glycerine ; and here I have had some 

 difficulty in finding a suitable substance, but I can now recom- 

 mend the following : — First apply one or more coatings of a 

 warm, thin solution of gelatin, and, after its having dried, immerse 

 the specimen for a few minutes in a solution of formalin, say of 

 10 per cent, strength, which will make the gelatin insoluble in 

 water, and so the specimen will be rendered impervious to damp, 

 and the glycerine consequently not subject to atmospheric 

 changes. 



By the above treatment all the articular membranes down to 

 the minute mouth parts and antennae will be found quite supple 

 and capable of being turned aside, or dissected off, for examina- 

 tion. The varnishing necessarily makes them stiffer than if left 

 without it. I submit for your inspection numerous examples 

 treated by the above process, both unvarnished and varnished, 

 including the soft-bodied Hermit Crabs, and examples of the 

 Dromidse with sponges and ascidians on their backs ; also, in- 

 cidentally, a few Sea-Urchins and Star-fish, including some Brittle 

 Stars, which are quite mobile. 



To make the process clear to all, I will now give detailed par- 

 ticulars for treatment of crustacean specimens : — 



Take a wide-mouthed glass fruit-jar, known as the " Chicago," 

 of a quart size, measure 8 ozs. of strong methylated spirit 

 and dissolve 7 grains of corrosive sublimate (a violent poison) 

 in it, then pour it into the jar and add 8 ozs. of water and 

 12 ozs. of glycerine, and shake the whole well together until 

 the glycerine is thoroughly diluted. This now will act as our 

 stock jar, and specimens may be immersed in it from time to time, 

 but after some use it should be strained, and a little more 

 glycerine, spirit, and sublimate added. It must be noted that a 

 metal container must not be used for this mixture, or the corrosive 

 sublimate will be reduced. 



As regards the time of immersion, this will of course depend 

 upon the size of the specimens, but they will not be injured if 

 kept indefinitely in it. With the more bulky ones, such as the 

 Fresh-water Crayfish, Astacopsis bicarinatus, and larger forms, a 

 small hole should be drilled in the carapace over the region of 

 the heart, and by a small glass syringe some of the mixture should 

 be injected through into the blood space, and a few punctures 

 made with the blade of a knife in the intersegmental membranes. 

 Ten days' immersion will suffice for Astacopsis. For specimens 

 of such a size as our common shore crab, Paragrapsus gaimardi, 

 and larger forms, slit the membrane that unites the carapace to 

 the reflexed abdomen (thoracico-abdominal membrane) on the 

 upper surface from one side to the other, and place in the 

 mixture for at least a week. Smaller forms may simply be 

 placed directly into the mixture, but in all cases they should be 

 cleaned from any dirt first, and preferably well rinsed with fresh 



