28. Wash with ammonia-free distilled water, dry thoroughly and mount in xylol balsam. ~Cranial and Spinal Cavities.~-- 29. In some instances it may be necessary (e. g., experimental inoculation of rabies) to examine the cranial cavity or to remove the spinal cord. Return the viscera to the abdominal cavity; draw the flaps of skin together and secure with Michel's steel clips. Draw the copper nails securing the limbs to the board, reverse the animal and again nail the limbs down--the body now being dorsum uppermost. 30. Make a longitudinal incision in the mesial line from snout to root of tail, and four transverse incisions--one joining the roots of the two ears, one across the body at the level of the spinis of the scapulæ, another at the level of the costal margin and the last across the upper level of the pelvis. Reflect these flaps of skin. 31. With forceps and scalpel dissect out the muscles lying in the furrow on either side of the spinal processes. 32. Cut through the bases of the transverse processes with bone forceps. Cut away the vault of the skull, cut through the roots of the nerves and remove the brain and spinal cord, place in a large glass dish for examination. Prepare cultivations from the cerebro-spinal fluid. The removal of the brain and cord is a tedious process and during the dissection it is difficult to avoid injury to these structures. The operation is, however, carried out very expeditiously and neatly with the aid of the surgical engine (_vide_ page 361). A small circular saw is fitted to the hand piece. The bones of the skull are cut through and the whole of the vault removed, exposing the entire vertex of the brain. Similarly all the spinous processes can be removed in one string by running the saw down first one side of the spinal column and then the other. In this way ample space for the removal of the nervous tissues is obtained with a minimum of labour. 33. Having completed the preparation of cultures remove small portions of various organs at leisure and place each in separate bottles of fixing fluid for future sectioning. Affix to each bottle a label bearing all necessary details as to its contents. 34. If necessary, remove portions of the organs for preservation and display as museum specimens (_vide_ page 404). 35. Gather up all the infected instruments, return them to the steriliser, and disinfect by boiling for ten minutes. [Illustration: FIG. 199.--Spear-headed platinum spatula (actual size.)] 36. Sprinkle dry sawdust into the exposed body cavities to absorb blood and fluid. Cover the body with blotting or filter paper, moistened with 2 per cent. lysol solution. Place in a galvanised iron pail, provided with a lid, ready for transport to the crematorium. 37. Cremate the cadaver together with the board upon which it is fixed. 38. Stain the cover-slip preparations by suitable methods and examine microscopically. 39. Incubate the cultivations and examine carefully from day to day.