32 TAXIDERMY AND MODELLING 



Organisms of a certain degree of firmness are plunged at 

 once into 70 per cent, alcohol, which is changed as stated. It 

 happens occasionally, although rarely, that, even after these 

 necessary changes, the alcohol becomes coloured again ; hence 

 it is necessary to change it often. 



When an organism is not sufficiently penetrated by alcohol, 

 it is necessary to shake the vessel containing it, to prevent the 

 formation of a body of weak alcohol in any position which 

 would cause the subject to break up. 



On the other hand, alcohol of a greater strength than 70 per 

 cent, does not preserve so well in the majority of cases, as it often 

 ends by becoming cloudy, and long immersion in such has a 

 tendency to cause the subject to become tender or to break up. 



Not only is alcohol of a lethal character, killing rapidly or 

 slowly as diluted, but it is, as these pages will show, used as 

 an anaesthetic. 



The greater number of the sponges may be fixed by merely 

 plunging them at once into alcohol of 70 per cent., and re- 

 newing it after twenty-four hours. 



Numbers of the Crustacea are well preserved in alcohol 

 ranging from 70 to 90 per cent. 



Such " Feather-stars " as Antedon {Comatuld) rosacea, Lo 

 Bianco (p. 458) plunges at once into alcohol of 70 per cent. 

 A. phalangium, however, breaks in this strength, and therefore 

 must be fixed and killed in alcohol of 90 per cent. 



Edwardsia, a genus of "sea-anemone," is narcotised slowly 

 by adding, little by little, alcohol of 70 per cent, to the sea- 

 water in which it lies extended, and is then killed with a hot 

 saturated solution of bichromate of mercury. 



The curious molluscs Doris and Chromodoris are narcotised 

 in exactly the same manner, and are killed by plunging them 

 into concentrated acetic acid or boiling bichloride of mercury 

 (Formula 16). 



