Fig. 8. Photograph of the cannula with inserted stilette (seen as bent wire protruding from 

 upper end) and protective screw cap. Scale in mm. 



.#'# 



Fig. 9. X-ray photograph of cannula in situ in head of rabbit. The stainless steel, anchoring 



screws may be seen in the vault of the skull, though the mound of dental cement fixing the 



cannula to these screws is invisible by X-ray photography. 



