MISCELLANEOUS NOTES. 249 



No. XXXIV.— THE PRESERVATION OF NATURAL HISTORY 

 SPECIMENS. 



With reference to Mr. Comber's interesting series of papers on the preserv- 

 ation of Natural History specimens, I should like to give you a few of my 

 experiences which I trust may prove of benefit to some members. 



FORMALIN. 



This is no doubt of the greatest service to the field naturalist when travel- 

 ling, as has already been pointed out, when spirit is not available. But it has 

 serious drawbacks. Fishes immersed for any length of time in this medicine 

 are apt to get brittle as regards their fins and tails. Mr. Boulenger at the 

 Natural History Museum was pointing this out to me the other day, and he 

 says it is exceedingly annoying when the identification of a particularly 

 valuable specimen is desired, to find when attempting to count the fin rays 

 this organ break right off. Formalin, too, is a dangerous medicine to recom- 

 mend to the tyro, who, ignorant of the right strength to use , will doubtless 

 ruin many a valuable specimen until he has learnt, as I have done, from sad 

 experience, the right proportions of formalin and water; and here no hard and 

 fast rule can be laid down. If used too strong specimens curl up in it. If 

 this be the case it can to a certain extent be remedied thus : — take out the 

 specimen from the formalin and soak for about 24 hours in water. Then dry 

 with a clean cloth and stretch the fish or other specimen out on a piece of 

 wood or stick fastening it to this by binding round with stout thread or string 

 Next immerse the specimen in strong spirit for several days after which 

 the support may be removed, and the specimen will then retain much of its 

 former straightness. Formalin also completely destroys the silvery and 

 golden lustre on many fishes. I have found it excellent for reptiles 

 batrachians, and have at the present time a lizard and snake which I kept for 

 over two years in a 25 per cent, solution of formalin. These were subsequently 

 transferred to spirit and to-day retain all their colours and marking as they did 

 when freshly killed. By the way I have found snakes "go wrong" more 

 quickly in spirit than any other specimens. Fishes I have kept for about three 

 weeks in a fairly weak solution of formalin and then transferred, retain much 

 of their natural brilliancy, but as colour is of little or no importance for the 

 determination of a species this counts as trifling. I would strongly urge 

 whenever possible the use of spirit and leave formalin — severely alone. For 

 soft bodied animals, such as tadpoles, jelly fishes, and the ova of frogs 

 formaliu is of the greatest use, but a very weak solution should be used, say, 

 about 4 per cent. These should be allowed to thoroughly harden in this before 

 being transferred to spirit. The colours of fishes, if desired, may be preserved, 

 to a great extent, so Mr. Boulenger informs me, by being kept in weak spirit 

 in the dark. But in a hot climate like India this is not always practicable. 

 My advice to the amateur would be to experiment with common specimens 

 first in different solutions of formalin and spirit keeping a careful watch daily 

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