PEEPARATIOy OF SKULLS. 107 



but a very short time to prepare a skeleton or a part of a skeleton. 

 (4) It is especially adapted for skulls, as the teeth are much less 

 liable to fall out, and the gelatinized dental periosteum serves as a 

 cement. (5) There is no danger of blood i)oisoning (septicaemia) if 

 fresh, healthy animals are used. There is no danger in any case 

 after the bones have been well boiled. 



§ 249. Bones are not satisfactorily cleaned by ants or Dermestes. The cleaning may be 

 very satisfactorily completed, however, by boiling in the mixture of liquid soap (§ 248). 

 The final cleaning of alcoholic specimens is best done in the same way. 



§ 250. Preparation of Skulls — A. Bi/ Maceration. — Separate 

 the skull, remove the skin, the eyes and the tongue. Then separate 

 the mandible, but let the os hyoides remain. With a tracer or a 

 piece of wire, inserted through the Foramen magnum (Fig. 57), 

 break up the brain, taking care, however, not to injure the project- 

 ing bony tentoriuim (Fig. 59). After the brain is broken up it 

 should be washed out with a syringe. 



Place the skull and mandible in the macerating dish so that the 

 teeth shall be uppermost ; then, if the water is changed carefully, 

 the teeth are less aj)t to fall out and be lost. 



The cleaning should be done as described above (§ 247), exce^ot 

 that greater care is usually necessary. 



B. By the Liquid Soap Process. — The skull should be prepared 

 as described for maceration, except that the mandible need not be 

 separated. Proceed as directed above (§ 248). 



Skulls can be much more quickly and safely prepared by the liquid soap process than 

 by any other. 



§ 251. Cements for Bones and Teeth.— The pelvis and man- 

 dible often separate at their symphyses, and the teeth may become 

 loose and be in danger of falling out. This latter is especially 

 liable to occur with macerated skulls. To unite bones, one should 

 use : — 



A. Liquid gelatin (see Formula, § 1446). Attach the bones 

 firmly by a rubber band or string while the gelatin is drying. The 

 method is the same as for gluing wood. 



Teeth may be fastened in their sockets by the same substance, 

 only it is unnecessary to bind them in while the gelatin is drying. 

 The skull should rest on its dorsal side, and the mandible on its 

 ventral side, so that the teeth may remain in place during the 

 drying. 



