i8o 



THE MUSEUM. 



cially pure) $2. 50 a gallon and when 

 diluted to seventy five per cent., the 

 proper strength for a final preserving 

 solution, costs about $2.00 per gallon. 

 Formalin, too, in its concentrated 

 form, occupies but little space, an add- 

 ed advantage to those who are going 

 into the field to collect. 



I have already stated that a three 

 per cent, solution is strong enough for 

 most purposes. In this strength I 

 have preserved all invertebrates, with 

 a few exceptions to be noted later, the 

 smaller reptiles and batrachia, most 

 fishes, many mammals and birds. In 

 very few cases have I ever lost mater- 

 ial unless through some oversight on 

 my part as packing too closely, not 

 properly injecting, etc. For sponges, 

 medusae, tunicates, large reptiles and 

 batrachians, large fish, mammals and 

 birds, and as an injecting solution, I 

 use five per cent. In my experience 

 five per cent, formalin works better in 

 these cases than three per cent. 



Great care should be taken to inject 

 all material, large enough to require it, 

 thoroughly. For this purpose I use 

 generally a bulb syringe with a glass 

 tube fitted to it, and in some cases 

 where an incision of any size would be 

 detrimental to the specimen, a hypo- 

 dermic syringe. Crabs should be in- 

 jected through a hole made under 'the 

 "purse" on the under side. Starfish 

 may be injected through a hole cut in 

 one ray. Nearly all the vertebrates 

 should be injected through the mouth 

 and anus and, if rather large, through 

 one or more cuts on the abdomen. 

 Medusae, sponges, tunicates, etc., will 

 not need injecting. A little experience 

 will teach the collector what speci- 

 mens he must inject and what ones do 

 not require it. In packing, specimens 

 should not be crowded for the first 

 day or two. After they have hardened 

 a little they may be packed fairly close 

 without danger of spoiling. I prefer 

 to change formalin on those specimens 

 where it has become much discolored 

 and probably weakened by the juices 



of the body, and consider this a good 

 rule to follow. This old formalin need 

 not be thrown away, but can be used, 

 strengthened a little if necessary, as a 

 first bath or as a' killing agent for 

 other specimens. 



It is not necessary to say that form- 

 alin should be kept in tightly closed 

 receptacles as it will lose strength rap- 

 idly. Before going further I might 

 say that it does not make much differ- 

 ence whether formalin is mixed with 

 fresh or salt water, but I think the 

 former a little the best. For marine 

 forms, however, I use a great deal of 

 salt water in mixing the formalin. 



As regards the lasting qualities of 

 formalin, I have specimens now that I 

 put up in 1895 and they are keeping 

 first rate. I see no reason why they 

 should not keep so indefinitely, pro- 

 vided the containing vials or jars are 

 kept tightly sealed or the formalin re- 

 newed at intervals of two or three 

 years. There is, however, one objec- 

 tion to the use of formalin in large 

 museums, where the temperature is 

 apt to get down to the freezing point. 

 The diluted Formalin will freeze and 

 this may injure the specimens contained 

 in it or perhaps damage the contain- 

 ing glass ware. I think I have seen 

 this objection spoken of in the report 

 of one of our large museums. 



As a killing agent Formalin acts 

 rather violently. Crabs are apt to 

 cast their claws when immersed in it 

 and it is better to kill them in most 

 anything else. I have tried it as a 

 killing agent on sea cucumbers (Thy- 

 one) but without much success. The 

 worms do not kill well in it. Three 

 are some things, however, like the 

 medusae and many of the tunicates, 

 which can be dropped directly in five 

 per cent, formalin with good results. 

 For reptiles and batrachians, fish, etc., 

 it answers very well. Bright colors 

 are almost sure to disappear in forma- 

 lin, though on some things, as snakes 

 for instance, it holds the color very 

 well. 



k 



