Hypo-pituitarism leads to a striking and rapid development of fat (adiposity), loss of sexual power and amenorrhœa, persistence of sexual infantilism (if the patient be attacked when young), harsh skin and œdematous tissues, subnormal temperature, and psychic disturbances. In any case, whether the secretion of the gland be increased or decreased, the developing tumour tends to compress those cranial nerves with which it is in close anatomical relation. For instance, the gland, being situated immediately behind the optic chiasma, tends to compress the mesial nasal optic fibres producing bilateral temporal hemianopia, with primary optic atrophy as a final result. In some cases optic neuritis is observed with secondary atrophy. The third, fourth, and sixth nerves may also be affected, with consequent squints, ptosis, and perhaps complete ophthalmoplegia. In addition, it should be noted that glycosuria and albuminuria have been observed. * * * * * In the _general diagnosis_ of brain tumours, reference must be made to _Lumbar puncture_ and _X-ray investigation_. =Lumbar puncture.= With respect to the desirability of carrying out lumbar puncture in brain tumours and the value of the information obtained, considerable difference of opinion exists. Lumbar puncture supplies information as to the tension of cerebro-spinal fluid and as to its bacteriological and cytological character. The evidence so obtained as to tension is of little value in view of the proved increase of intracranial pressure as evidenced by the mental condition of the patient, the headache, optic neuritis, &c. On the other hand, bacteriological and cytological examination of the fluid may point to the tuberculous or syphilitic composition of the tumour, thus offering help from the point of view of treatment. Still, information of almost equal importance can be obtained by tuberculin, Wassermann, and other tests. There is also considerable risk attendant on the process. The rapid withdrawal of cerebro-spinal fluid has been followed by disastrous results, the medullary stem being suddenly forced downwards into the foramen magnum, with corking up of that aperture, and complete upset of the medullary centres. Such a disaster is the more likely to occur when the tumour is subtentorial in position. Looking at the question from the broadest point of view, it would appear that the performance of lumbar puncture in cases of suspected brain tumour is fraught with considerable peril.