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382 H^ Goadhy on the Preservation of Animal Siihstayices 



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I believe that the interior 



fore alluded to, because, if so, I think there would be considera- 

 ble deposit in the fluid, which has not occurred ; neither in that 

 case would the insect retain its roundness, and fullness, but on the 

 contrary become flaccid by the removal of those tissues (muscles) 

 tliat give form to the integument. As this caterpillar had been 

 secluded from the operation of light (the fruitful agent for de- 

 stroying color in animals) for more than twelve months, I deter- 

 mined to try the efl'ect of constant exposure, to which I submit- 

 ted it for three years in England, and for six months in this 

 country ; its beauty is still unimpaired. As it is a sole specimen, 

 and I am not likely to obtain another, I am unwilling to dissect it. 

 I have been particular in speaking of the successful application 

 of arsenic in the preservation of color in this caterpillar, because 

 I believe it is of some importance. It is most interesting to col- 

 lect the larvas! of Lepidopterous and other insects, as far as pos- 

 sible, but they lose much value for the purpose of instruction and 

 for collections, unless their color Can be permanently preserved ; 

 and I have great hopes that the fluid which has proved so emi- 

 nently successful in the instance of the caterpillar of the goat- 

 moth, which takes on the described blackness a very few days 

 after death, in every other preserving fluid, may be equally efiica- 

 cious in the preservation of color, in the other species. 



Mode of using the Preserving Fluids. — A knowledge of the 

 proper methods of using the fluids is essential to success, for 

 in other hands than my own, they have led to the destruction 

 rather than the preservation of specimens. Men have constantly 

 treated my preserving fluids as though they were using spirit, 

 ^tirely overlooking one very important consideration, namely, 

 the vast difference between their specific gravity and that of alco- 

 hol. In the latter, we have a fluid so light that every animal 

 IS heavier, and will instantly sink in it; the conditions are ex- 

 actly reversed in the former case, where every animal, from an 



aninrialcule to an elephant, is lighter, and will float upon either 

 of them. 



Neither of my fluids (always excepting the arsenical) can he 

 employed of fall strength in the first instance, and any thing to 

 be preserved m them should undergo previous maceration in 



A^'^A ^^^^'"' *° '^'^^^^' ^^*®^ * t™e> preserving- fluid may be 

 added until the animal rises to the surface. The fluid and the 

 \yater must be intimately mixed mechanically, or the water will 



rise through the denser fluid, and retain its integrity for a long 

 time. 



The animal will insensibly absorb, and become saturated with, 

 the liigredients of the preserving fluid, but in a state of considera- 

 ble dilution; the strength of the fluid must now be gradually in- 



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