408 APPENDIX. 



ney of the sheep. Several of these shohld be procured and 

 opened in various directions to show the structure (Fig. 93). 



CHAPTER XVI. 



With little trouble skeletons of frogs, birds, and mammals 

 with bones connected by flexible attachments may be prepared. 

 Carefully cut away all of the muscles and other soft parts, leav- 

 ing only the ligaments connecting the bones. Then place the 

 roughly prepared specimen for one or two weeks in Wicker- 

 sheimer's fluid, which is prepared as follows : In three litres of 

 boiling water dissolve 100 grammes of alum, 60 grammes of 

 caijstic potash, 25 grammes of salt, 12 grammes of saltpetre, 

 and 10 grammes of arsenic. Cool and filter the liquid. Then 

 to each litre of the fluid add 400 cubic centimetres of glycerine 

 and 100 cubic centimetres of alcohol. The ligaments of skele- 

 tons soaked in this fluid will remain flexible during many 

 months of exposure to the air. Should the ligaments become 

 stiffened, their flexibility may be restored by a few hours' im- 

 mersion in the fluid. 



CHAPTER XVII. 



Muscle fibres for microscopic examination may be obtained 

 from the leg of a frog, or even from the body of a recently 

 killed animal at the meat-shop. Lay a small piece of muscle 

 in a drop of .75 per cent, salt solution on a glass slide, and with 

 a pair of dissecting-needles carefully pick the muscle to pieces. 

 Some of the smallest shreds, upon examination with a one-fourth 

 or a one - sixth inch objective, will be seen to be single or 

 grouped muscle fibres, which will show the striations and the 

 sarcolemma (Figs. 11, 12). 



CHAPTER XVIII. 



Nerve fibres are readily obtained from the sciatic nerve in the 



