176 



KNOWLEDGE. 



May, 1911. 



fall back on such books as " .Mi\ai"t's Lessons in 

 Elementary Anatomy," which contain good diagrams 

 and lucid desgriptions of the \-arious regions — if not 

 actually of every animal, at least of so many types 

 that almost any skeleton ma\' be prepared from 

 them. I have appended a list of books which will 

 be of use and easil\- obtained. 



To start with the dissection. This is an art 

 which cannot be taught : it can onh' be learned b\' 

 patient and plodding labour. The toad should be 

 dissected carefulh' and thoroughly, with the aid of a 

 book. .\11 the structures and organs should be 

 noted, and drawings made at the different stages of 

 the dissection, especially of the muscles and liga- 

 ments. When satisfied that the soft parts have 

 been properly studied, as much of the flesh as 

 possible is cut from the bones, and the ligaments 

 are carefully examined. 



The body must now be macerated. This process 

 consists of soaking the bmh- ui water for an 

 indefinite period. For this i)urpose zinc tanks are 

 useful (never iron or tin), of the following dimen- 

 sions : 1-in. long. 3-in. wide, 1^-in. deep, for small 



animals: and 6-in. long. 4-in. wide, and i^-in. deep 

 for larger animals : these shoukl alwa\'S have tight- 

 fitting lids. A useful substitute. howe\er. is a pie 

 dish or other shallow earthenware vessel, covered 

 with a sheet of glass. It is often advisable to 

 macerate the bod\' in sections, taking care always 

 to keep together the bones of similar regions. 

 Esjjeciaily is this method useful with larger animals, 

 as in this case the quantit\- of flesh one is obliged to 

 lea\'e on the bones after dissection is often con- 

 siderable, and b)- putting them into separate tanks 

 one obtains a larger mass of water to each bone, 

 and so expedites the process of rotting. The hands 

 and feet should ahvays be cut off at the joints, and 

 each macerated separateh' in a small earthenware 

 or glass jar. While it is macerating, the specimen 

 needs frequent attention. The vessel should alw■a^•s 

 be kept covered when one is not actually working on 

 it, and the specimen must never be allowed to dry uj). 



As soon as the bone is loose and all flesh on it is 

 soft, it is taken out and put aside in fresh water or 

 preservative (weak spirit or formaldeh\de solution) 

 after it has been carefully cleaned. I do not advocate 

 retaining the ligaments. These should be studied in 

 the fresh condition, unless the object of the 

 preparation be essentialK- to display them. Should 

 one wish to keep them, the macerating si)ecimon 

 will need careful watching, and it must be taken out 

 of the tank immediateh- when an\- ligaments show- 

 signs of coming away from the bones. Should anv 

 flesh still be adherent, it should be scraped oft' 

 gently with a scalpel. LSut for the preparation in 

 question, viz. : the toad, the ligaments are not 

 required. When macerating do not remo\-e too much 

 of the debris at first, as bv so doing the bacterial 

 action is liable to lie retarded. After decom- 

 position has thoi-oughl\- conuueiiced it isad\isable to 

 take out some of the rubbish from time to time. 

 For this purpose an old table fork is ver\' useful. 



.\s one takes out the bones they must be cleaned. 

 This is a \er\' tiresome and delicate process. 

 E.xcept for large bones the knife should not be 

 used. A camel-hair brush, an oil-painter's flat 

 bristle brush with the bristles cut down to about a 

 quarter of an inch : a couple of needles mounted in 

 handles : a pair of fine forceps ; and a pair 

 of fine-pointed scissors, cur\'ed on the flat, are 

 the necessar\- instruments. An\- stubborn fibres 

 of ligament should be cut off close with the point of 

 the scissors ; the flesh and debris are brushed off with 

 the hard brush, and the bone is finished l)y brushing 

 with the soft brush. The brush should always be 

 used in one direction onl\-, not to and fro. The 

 bones should ah\a^•s be held in the forceps — never 

 in the fingers, and the w hole cleaning should be done 

 as far as possible under water. A piece of ground 

 glass, made to fit the bottom of the cleaning vessel 

 and with its smooth surface blackened w ith jiaint, so 

 that the colour shows dull through the ground 

 surface, is very useful as the bones show up clearly 

 upon it when one is cleaning them. If after cleaning, 

 some pieces of flesh still adhere tightly to the bones, 

 tlie\- must be macerated further. 



It sometimes happens that the ligaments will not 

 \ ield to maceration : especially is this the case with 

 the hands and feet of all vertebrates and the 

 vertebrae of Ophidia. In this case boiling becomes 

 necessarw The bones should be boiled in a small 

 enamelled saucepan, the smaller the better. Before 

 putting thi-m into the saucepan, a few drops of strong 

 solution of caustic potash ma\- be added to the 

 water ; ver\- little should be usetl and the potash 

 should never be added in solid form, because it 

 takes some time for it to diffuse and the specimen 

 is liable to injur\' through coming in contact 

 with a \er\- strong solution. The liquid potash 

 should be added to the water, droj) by drop, 

 and the whole well stirred before putting in the 

 bones. 



The ligaments will often soften b\- just bringing 

 them to the boil, and the specimen must ne\-er be 

 boiled for more than a quarter of an hour. It is not 

 ad\'isable to boil the bones clean ; they should be 

 cleaned, in the manner mentioned above, after 

 boiling. 



The next process after cleaning is bleaching. 

 \Mien all the bones are clean they should be washed 

 free from any preservative — if such has been used — 

 with distilled water. They are then placed in a 

 glass vessel in a 1 in 20 solution of hydrogen 

 pero.xide. The strength is made by mixing the 

 strong solution ordinarily sold, with 19 parts water. 

 This does not of course represent 1 part H, O2 in 20 

 of water. The vessel containing the bleaching bones 

 shLiuld always be kept co\-ered with a sheet of glass 

 so that no oxygen is lost. Never use chloride of 

 lime for bleaching as 't injures the bones and 

 destro\'s the markings. 



The vessel should be broael and shallow so as to 

 obtain the greater surface area, and it should be 

 [jlaced on a white surface so that the light is rellected 



