46 TAXIDERMY AND MODELLING 



although it, Hke many other fluids, preserves reptiles without 

 much change, yet its chief and most valuable property appears 

 to be that of efficiently preserving objects subsequently treated 

 with potassium bichromate. Specimens of fishes, etc., preserved 

 by this salt, having been decolorised, as subsequently stated, by 

 lengthy and constant soaking in water, have been transferred 

 into a 5 per cent, solution of formol without any appreciable 

 change or the formation of any precipitate. A few months 

 only having elapsed, it is, taking into consideration its chemical 

 instability, not possible to say more in its favour at present, 

 nor is it known as yet how it would behave with soft or 

 gelatinous invertebrata ; it is stated, however, that the following 

 organisms are well preserved by formol ^ in the strengths given 

 therewith : — Protozoa, in a 6 per cent, solution ; the larger 

 Medusae, Rotifera, and some of the fleshy Polyzoa, 5 per cent. ; 

 some of the Crustacea, 8 per cent. ; Mollusca, 5 per cent. ; 

 Cephalopoda, 4 per cent. ; Tunicata, 6 per cent. ; Amphioxus, 

 Dogfishes, etc., 4 per cent. 



Acetic Acid. — This is known to Lo Bianco (p. 441) as a most 

 penetrative fixing reagent, and it kills rapidly many contractile 

 organisms, but in some cases should be used in its concentrated 

 form. It certainly, however, failed to fix rapidly enough — 

 although it killed — some extended snails which the writer 

 experimented upon. Needless to say, subjects must not be left 

 long under its influence. 



Medusae, such as Olindias mUllerii, are, says Lo Bianco, 

 fixed with the above acid, and immediately transferred into 

 chromic acid of i per cent., where, with small pliers, their mar- 

 ginal tentacles are displayed before being placed in alcohol. 



Large " sea-cucumbers "■ — Holothuria and Stickopus, — when 

 their buccal tentacles are fully extended, should be seized with 



^ 1 See " The Use of Formalin as a Preservative Medium for Marine Animals," by 

 James Hornell, Natural Science, vol. vii. (No. 46), pp. 416-420. 



