PRESERVATION OF THE POLYPIDOMS OF ZOOPHYTES. 509 



process. In mounting the specimens, liquid balsam must 

 be employed, and only a very gentle heat should be ap- 

 plied ; and if, after it has been mounted, the section 

 should be found too thick, it will be easy to remove the 

 glass cover and reduce it further, care being taken to 

 harden the balsam, as directed in preparing bone sections. 



PRESERVATION OF THE POLYPIDOMS OF ZOOPHYTES. 



The following excellent and simple plan for preserving 

 zoophytes as fluid preparations^ so as to retain the polypes 

 and their tentacular arms in situ, was adopted by the late 

 Dr. Golding Bird. For this purpose a lively specimen 

 should be chosen, and then plunged into cold pure water ; l 

 the polypes are killed almost immediately, and their ten- 

 tacles often do not retract : proper-sized specimens should 

 then be selected, and preserved in weak alcohol. Little 

 phials about two inches long should be procured, made 

 from thin flat glass tubes, so as to be half an inch w T ide, 

 and about a quarter of an inch, or even less, from back to 

 front. The specimens should be fixed to a thin platinum 

 wire, and then placed in one of these phials (previously 

 filled with weak spirits), so as to reach half-way down. 

 When several are thus arranged, they should be put on a 

 glass cylinder, and removed to the air-pump. On pump- 

 ing out the air, a copious ebullition of bubbles will take 

 place ; and many of the tentacles previously concealed 

 will emerge from their cells. After being left in vacuo 

 for a few hours, the bottles should be filled up, closely 

 corked, and tied over, like anatomical preparations in 

 general. For all examinations with a one or two-inch 

 object-glass, these bottles are most excellent, and afford 

 cheap and useful substitutes for the more expensive and 

 difficultly-managed cells. In this manner, specimens of 

 the genera Membraniporce, A Icyojiidce, and Crisiadce, &c, 

 exhibit their structure most beautifully. 



A few dozen of these little bottles hardly occupy any 

 room, and would form a useful accompaniment to the 

 microscopist by the sea-side. Any one visiting the caverns 



(1) A small quantity of gin thrown into distilled water answers the purpose 

 better than pure water, and specimens may be put up in the same. TLe animals 

 are nearly always preserved in their polypidoms by using this fluid to kill them. 



