18 THE VICTORIAX NATUHALIST. 



thill layer of loaded cork, or any other contrivance to keep it from 

 floatini(. The specimen is now ready to be placed in the chromic 

 acid solution, which must be made very weak to start with, as if 

 made strong, it would harden the outer parts too rapidly, and so 

 prevent thorough saturation. I begin with a solution of a pale 

 sherry colour, making it on each successive application a little 

 deepi-'r in colour, and so stronger. This Frog was kept 5 days in 

 the chromic acid solution, and during that time it was only once 

 changed. After removal from this solution the specimen was 

 washed in water, so as to get rid of the excess of acid as much as 

 possible before placing in alcohol. The methylated alcohol is used 

 weak at first, about 50°, and kept at this strength for a time or 

 two mi til tlie specimen ceases to colour it. The acid is but slightly- 

 soluble in strong alcoliol, hence that is only resorted to latterly, 

 finishing up witli absolute alcohol to remove every trace of water. 

 Tlie alcoholic treatment extended over 4 days, with at least as many 

 changes. The specimen was now hardened and dehydrated, and 

 after exposure to the air for a little to allow the spirit to evaporate, 

 it was transferred to pure oil of turpentine. After lying in this for 

 3 days without any change, (although less time might have served), 

 the Frog was afterwards dried, and proved to be a perfect specimen, 

 thereby showing the efficacy of the treatment. In this case the 

 internal organs are all in their natural position, but if desired, they 

 may be laid out to advantage before hardening, and then the 

 specimen becomes more valuable for purposes of instruction. 



I need not give details about other specimens preserved, among 

 which were rabbit, pigeon, chick, mouse, cuttlefish, snail, slug, 

 mussel, whelk and worm, besides brains, hearts, lungs, &c. Small 

 and soft-bodied animals such as worms, snails and mussels may be 

 preserved entire without any pi-evious preparation, by simply placing- 

 them in the fluids. When killed with chloroform w:irms and snails 

 usually stretch themselves out to their full extent before giving up 

 the ghost, which is a decided advantage to the preserver. The acid 

 acts upon calcareous structures isucli as shells, and so they are 

 removed. Animals may be kept in spirit before being treated to 

 this process, and so a number of specimens may be collected and 

 done together. It is a saving of time and material to do several at 

 once, and in the case of Museums, the oil might be used over agaiu 

 by distilling it, while the alcohol last used might be employed at aa 

 earlier stage with other specimens. 



It is easiest, of course, to do comparatively small animals, bufc 

 pigeons, rabbits, cats, &c., only require more changes of fluid and 

 longer immersion. With larger spieciinens still, the difficulty is to 

 get the hardening fluid to ijenetrate, but that might be overcome by 

 injection. I think it quite practicable to prepare specimens up to 

 the size of the human body. 



