water pending return to base-camp or laboratory. Here each stick and 

 slide should be carefully examined to ascertain whether all the animals 

 remain well tied or have perchance begun to slip their moorings, as they 

 sometimes do by crawling from under the cord. All such should be retied 

 and then the whole may be immersed in weak alcohol for an hour or two, 

 or in ordinary tap water for a longer period. My own results have been 

 best under the former procedure, after which the animals may be passed 

 through two or three changes of alcohol in ascending concentrations, 

 remaining in each for a period of perhaps 10 or 12 hours, until they are 

 brought into a solution of 70 to 75 percent strength, which is sufficient for 

 their permanent preservation. More concentrated solutions of alcohol only 

 serve to harden and warp the tissues and should be avoided. After the 

 specimens are in the 70 percent alcohol they may be untied from their 

 temporary substrata and will thereafter retain their natural outlines if 

 allowed to lie free and not too closely crowded in the preserving medium. 



In my experience formalin is an exceedingly unsatisfactory, even 

 objectionable preservative for chitons. Its advantages in the way of retain- 

 ing beautiful colorings are far outweighed by the damage done through 

 softening or dissolution of important calcareous parts. Do not use it. 

 Should it chance that nothing else is available, however, no pains should 

 be spared to transfer the specimens preserved in it to 70 percent alcohol 

 at the earliest opportunity. Methyl (wood) alcohol likewise is not to be 

 recommended as anything but a wretched makeshift, while even denatured 

 ethyl alcohol is very much less satisfactory than the pure article, particularly 

 if the denaturant used is appreciably acid in character. If the specimens 

 are desired for histological work, more careful methods of fixation and 

 hardening should be undertaken, though even for this purpose I have 

 sometimes had surprisingly good results with no more refinement of method 

 than the simple procedure outlined. Ryder, in Dall's well known pamphlet 

 of "Instructions for collecting mollusks" (1892: 43), gives some excellent 

 "Directions for preserving the soft parts of Mollusca," and to these as well 

 as some of the better current manuals of microscopical technique I would 

 refer the reader who desires to pursue the matter further. 



If it be desired to preserve the specimens in the dry state, the animals 

 may be killed in weak alcohol or fresh tap water as previously suggested, 

 then unbound, the soft parts carefully cut away with a sharp knife and the 

 "shell" (i.e. the neatly cleaned valves enclosed in the girdle) firmly retied 

 to its stick in the flat natural position of the animal until the girdle has 

 thoroughly dried, and there is therefore no further risk of the specimen 

 curling or warping. Specimens dried on glass occasionally adhere so strongly 

 to the smooth surface that it is a little troublesome to lift them oflF undam- 

 aged, but the extra pains are worth while in that the girdle of such speci- 

 mens remains expanded and does not wrinkle against the valves as in the 

 common run of collectors' shells. Exceptionally beautiful museum specimens 

 are often the result. I do not consider the frequent practice of some col- 

 lectors of brightening up their specimens by the application of thin coatings 

 of vaseline, oil, or varnish to the dorsal aspect of the shell as one in any 



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