The _frontal route_ is strongly advocated by Krause.[50] He states that, ‘an osteoplastic flap is framed in the frontal region, immediately to one side of the middle line, so as to avoid the superior longitudinal sinus and frontal air sinus, and turned upwards. It is essential that the operator should approach the tumour along the floor of the anterior fossa, and, for this purpose, it may be deemed necessary to chip away the bone in the region of the supra-orbital ridge. Some days later, the final stages of the operation are conducted. The dura mater covering the frontal lobe is stripped away from the bone and traction applied to the dura by means of broad flat spatulæ. When the lesser wing of the sphenoid is exposed, the dura mater is opened in the vertical direction on a line with the lower median angle of the wound at a depth of 5 to 5¹⁄₂ centimetres, as measured from the anterior surface of the frontal bone. If the incision is made at a deeper point there is danger of injury to the optic nerve, which is covered with dura mater in this situation. Laterally the dura is opened parallel to the posterior border of the lesser wing of the sphenoid, about ¹⁄₂ cm. in front of it, to avoid the sinus which lies immediately in contact with the edge of the bone. This exposes the optic nerve, coming from the chiasma and the internal carotid. The pituitary body is located beneath the anterior edge of the chiasma. The diaphragm of the sella turcica is now carefully incised with a small hook-shaped scalpel, and the hypophysis is readily removed.’ The _nasal route_, advocated by Bruns and successfully carried out by Schloffer[51] and Cushing, seems to offer the greatest advantages and give the most successful results. The general details of the operation are as follows: starting either beneath the upper lip or externally at the base of the septum, the mucous membrane is peeled away from each side of the vomer, and, by gradual piecemeal removal of that bone, the advance is carried out towards the base of the skull in what may be called an intra-mucous space. By the introduction of suitable instruments into this space the cavity is gradually enlarged, at the expense of the turbinated bones which are compressed by the dilating instruments. By this means--gradual removal of the septum--the operator approaches the base of the skull, always working between the two layers of mucous membrane, and always avoiding, with the greatest care, any laceration of the same. Laceration at once converts the more or less aseptic operation into an infected one. When the base of the skull is laid bare in the region of the sphenoidal sinus, the bone is there chiselled away and the under surface of the pituitary body exposed. It can then be removed piecemeal.