4i8 NATURAL SCIENCE. dec. 



The Lucernariidae — except for histology — should always be 

 preserved in formalin, the results are so good. In this case, previous 

 stupefaction is necessary. 



Ctenophora. — Cydippe and Beroc are not satisfactory in 

 formalin ; they seem unable to attain sufficient toughness to allow 

 them to sustain their own weight in the fluid. 



EcHiNODERMATA. — Spirit and formalin are about equal in results. 



Enteropneusta.— jBa/rt/Zfjo'/ossi/s is worthless in formalin, as it 

 secretes too great an amount of mucus, and spirit is necessary to 

 coagulate this. 



Vermes.— The Turbellaria can only be preserved in spirit. 

 Nemertines and Polychaetes, if previously well fixed, are very 

 satisfactory in formalin, but the use of 50 per cent, spirit fortified with 

 5 per cent, formalin is even better. Such, however, of the Polychaetes 

 as secrete much mucus, e.g., Chcrtoptenis, must be preserved in the 

 ordinary way by passing into strong spirit. Formalin has little or no 

 hardening action upon vmciis. 



Some of the smaller Nemertines are killed very well extended by 

 being thrown into formalin. 



Rotifers preserve beautifully in formalin if previously fixed in 

 corrosive sublimate. 



PoLYZOA. — For fleshy forms, such as Alcyonidinm, formalin is most 

 useful, obviating the dull opacity of spirit specimens. 



Crustacea. — For all except those with a well-marked carapace 

 [Leptostraca, Thoracostraca, etc.), an 8 per cent, solution gives beautiful 

 results, transparency and pliability. Where, however, a carapace is 

 present, this frequently rises, giving an unnatural gap between the 

 posterior margin of the carapace and the succeeding segment. For 

 museum purposes, this is unsightly, but for dissection work there is 

 the counterbalancing advantage of giving the preservative fluid freer 

 admission to the organs beneath the carapace — always a difficult 

 point in the preservation of Crustacea. 



Mollusca. — Almost without exception formalin is vastly superior 

 to spirit for these animals, and ordinary fixing is quite immaterial — 

 without becoming intensely hard, as they do in spirit, an agreeable 

 firmness, very useful in dissection, is produced. While previous 

 anaesthetising is in no way superseded in the majority of cases, the 

 cephalopods are simply magnificent if transferred direct to a 4 per 

 cent, solution, and I dare prophesy that when once these formalin 

 preparations are seen by our museum authorities there will be a 

 general turning out of the old spirit specimens. 



TuNicATA. — Very good and natural results are here obtained if 

 the animals be previously thoroughly stupefied. A weak solution of 

 formalin must be avoided with the delicate species, say anything less 

 than a 6 per cent, strength. BotvyUiis in spirit is a depressing object- 

 lesson of how not to preserve naturally, and though the greater part of 

 the colour fades in formalin, yet the way in which all distortion of the 



