COLLECTING AND PRESERVING 307 



show its form; and the drab variety will, in formalin solution, 

 retain colour, and by good fortune more than by skill the 

 common " Beadlet " (Actinia mesembryanthemum) may 

 sometimes be managed. 



The Hydroid zoophytes, although usually represented in 

 collections by their polypidoms only, can be well preserved 

 in full expansion, and make beautiful preparations. To 

 kill these in expansion, either as specimens in jars or for 

 microscopic slides, as described later on, the usual plan 

 is to add, drop by drop, to the jar of sea- water in which they 

 are living some anaesthetic or fixative. The following will as 

 a rule answer : solutions of cocaine, chloral hydrate, chloro- 

 form or corrosive sublimate ; but the plan I usually employ 

 is to gently pour a layer of ether (which floats) on to the 

 surface of the sea-water, cover tightly with a piece of 

 bladder, and leave them undisturbed for a day or so, or 

 until it is seen on close examination that the tentacles do 

 not move, and then add a strong solution of corrosive 

 sublimate to harden them, after which they can be trans- 

 ferred to the preservative. If for museum jars, to show 

 mode of growth and polyps, formalin ten per cent, 

 is best. 



I have before me a jar with a cluster of Plumularia 

 similis in which every polyp is expanded and erect, just as 

 in life. This was prepared as just described. The pre- 

 servative is ten per cerit. formalin in sea-water, but tap 

 water will do. If spirit is used, as it must be if they are 

 being prepared to make micro slides of them, it must be 

 added by degrees, the simplest plan being to have the jar 

 only part filled with water (not sea-water), and then every 

 few hours add a little spirits of wine, until it is about seventy-, 

 five per cent, of the whole. Then they can be put into the 

 strongest grade for dehydration. 



The Hydro-medusids, or alternate generation of the 

 hydroid zoophytes, and also the larger forms Amelia, 



