90 PRESERVATION OF MEDUSiE. 



structure of the central peduncle. Conveying our prizes then to a dark place, we irritate 

 them, and observe whether they phosphoresce or not, of what colour the Ught is, and how 



long it endures. 



In every case a drawing, as careful and detailed as possible, and always coloured, should 

 be made at the time. This is the more necessary, since they are animals extremely difficult 

 to preserve, shrivelling up into indistinguishable curd-like masses in spirits, and most 

 preserving fluids. In fact, the only specimens which I have seen preserved in a distinguishable 

 state, have been so by means of one of Mr. Goadby's fluids. When Mr. Goadby accompanied 

 Mr. M' Andrew, in 1837, on a cruise among the Hebrides and Zetlands, he made many 

 experiments on the preservation of these deHcate creatures, and succeeded so well that I have 

 been able to distinguish among them even the several species of the critical genus Thaumantias. 

 I do not despair of seeing, before very long, a series of these creatures so preserved exhibited 

 in the British Museum, and contributing to render more perfect the finest natural-history 

 collection in the world. The indefatigable director of the zoological department in that truly 

 national establishment, will yet, I trust, sanction such an addition, and, as he no longer 

 remains a sceptic in bones or disbeliever in spirits, may consistently extend his faith to 

 Goadby's fluid. 



Note. — Kindly communicated by Mr. Goadby. 



To 'preserve the Acalepha. — These animals contain so large a quantity of water, that they 

 require great care and attention to preserve them. 



The B fluid of itself is not enough for the purpose, the assistance of alum being imperatively 

 necessary to give firmness and support to the several tissues. 



The plan that I adopted with great success was the following : i. e. 



Make a saturated solution of bay salt, and when cold, test it with a specific-gravity bubble 

 prepared for that purpose. 



When required for use, dilute it (with water) to 1148, indicated by another bubble so marked. 

 To this latter fluid add alum, at the rate of ^ij to every quart of fluid, and dilute the whole to ^ strength 

 with water. Pour this into a dish, and empty the contents of the tow-net (containing the well-drained 

 specimens of Acalephse) into it, and let them macerate therein for twenty-foTir hours, by which time 

 they will be found saturated with the fluid, and at the bottom of the dish. If the specimens be small, 

 they should now be moved, and placed in fluid consisting of dissolved bay salt, only to the strength of 

 1148, as the alum destroys transparency. 



Large specimens of the Acalephse, as Aurelia, &c., off'er exceptions to this rule ; they may be 

 allowed to remain in aluminous fluid (to be changed daily) of the strength described, or somewhat 

 increased by additions of stronger saline fluid, for a longer period (two or three weeks), but ultimately 

 they, too, must be removed from the continued influence of alum, and kept in the bay salt fluid, of not 

 less strength than before described, viz. 1148. 



The fluid should be tested with the bubble daily, and its strength made up by additions of the 

 saturated solution, until it obey the test for several consecutive days, when endosmose and exosmose being 

 at an end, the process of preservation may be considered complete. 



For permanent preservation, corrosive sublimate should be added to the preserving fluid, in the 

 proportion of grains ij per quart of fluid, but its use is unnecessary in the early stages of preservation. 

 I did not employ it until the collection of last summer was complete, and on shore. Neither is it 

 essential to filter the fluid if time be pressing : at sea, of course, it cannot be done. Finally, marine 

 animals require for their preservation saline fluid of the specific gravity of 1148. Fresh water and 

 terrestrial animals are preserved at the diminished strength of 1100; fluids of less strength (respectively) 

 are insuflicient, and greater strength is injurious. 



