six hours in alcohol of 35 to 50 per cent, according to their 

 consistency, and then be transferred to that of 60 per cent, 

 and afterwards to that of 70 per cent. If the preparations 

 are too delicate to bear handling, the transfer may be made 

 by pouring off the liquid and adding the proper amount of 

 alcohol to make a 35 per cent solution, continuing the process 

 until the standard strength is attained. When necessary to 

 avoid disturbing the animal at all a siphon may be used in 

 effecting the transfer. Frequently it is necessary to change 

 the alcohol after a few days, on account of discoloration. 

 Some forms are immersed directly in 70 per cent alcohol, 

 the liquid being changed after a few days. Changes should be 

 made until the alcohol remains colorless. When an animal 

 which has been in alcohol is transferred to that which is 

 stronger, it is necessary to agitate the jar from time to 

 time to avoid the formation of a layer of weaker alcohol on 

 the bottom. 



Many liquids have been tried at the station in search 

 for a possible substitute for alcohol, but always with poor 

 results. Some liquids, like those of Goadby and of Owen, 

 when used on gelatinous forms, eventually produce contraction 

 and consequent distortion. Wickersheimer 's solution, which 

 was highly praised when first brought out, distorts or macerateB 

 marine animals. Alcohol of 70 per cent is preferable for the 

 permanent preservation of animals for the reason that it is 

 sufficiently absorbed by the tissues after repeated changes. 

 A stronger solution not only is unnecessary for good preserva- 

 tion in the majority of cases, but it is even harmful in some, 

 because it eventually hardens the objects too much and renders 

 them brittle. Alcohol is useful, furthermore, for narcotizing 

 animals and for killing them slowly or quickly. 



Formalin or formaldehyde . — Formalin is a very useful 

 liquid for keeping animals temporarily, but not for preserv- 

 ing them permanently. Some pelagic animals — for example, 

 certain Medusae, Pterotrachaidae, and Salpidae — may remain 

 in it for even two or three years without serious detriment, but 

 if they are not transferred to alcohol by that time they begin 

 to disintegrate or decompose. Formalin therefore may be used 

 on a voyage or a long journey when alcohol is scarce or not 

 to be had. As a provisional fluid it is useful for many 

 other animals which are not contractile, and especially for 

 those which contain no lime spicules, skeleton, or shells. 

 Shell-bearing mollusks, echinoderms, and such things, can not 

 be preserved in formalin on account of the free acid in the 



It is said by the advocates of the use of formalin that this 

 free acid may be neutralized by sodium carbonate and many of the 

 objections to the fluid thus removed. 



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