434 ANATOMICAL TECHNOLOGY. 



and through corresponding points upon the basi- and supraoccipital 

 bones. 



1119. As already indicated ( 1114), the brain may be har- 

 dened while in the cranium. Each half should be loosened a little 

 as presently directed, and 95 per cent, alcohol injected between the 

 dura and the brain at two or three points. The half heads may 

 then be placed in 62-67 per cent, alcohol for two days and then 

 transferred to 95 per cent. 



Usually, however, the brain should be removed ( 1121), and the 

 dish of alcohol should have a flat bottom, or a piece of flat glass 

 should be placed in it, so that the hemiencephala may rest upon 

 their mesa. The operation will be facilitated by reference to a 

 hemicranium or to a figure of its ental aspect. 



1120. Weighing. (A) Direct method : As soon as the hemi- 

 encephala are in the normal saline solution, lift them out by means 

 of a slip ( 95), upon which their mesa should rest, let the liquid 

 drain off, and place them, still upon the slip, upon the weighing 

 pan. Upon the other pan place a similar slip which has been 

 dipped in the same liquid. 



(B) Indirect method : Just before removing the brain, and after 

 snipping off the falx, weigh the two halves of the head. Weigh 

 the hemicrania immediately after the removal, and the difference 

 will represent the weight of the brain. 



1121. Removal. Wash the mesa with a gentle stream of water, 

 or by movement to and fro in a dish of water. If the falx (Fig. 88) 

 is upon this side, grasp the edge with the forceps, and snip it along 

 its attachment to the skull. Note the position of the tentormm, of 

 the fossa olfactoria, and of the foramina upon the prepared skull ; 

 also, upon a figure, the ectal origins of the cranial nerves. 



Hold the skull with the venter upward, and gently push the 

 medulla mesad with the tips of the scissors. Out the N. Tiypoglos- 

 sus close to the dura. Successively cut the NN. accessorius, vagus 

 and glossopTiaryngeus as they enter the Fm. jugulare. Tilt the 

 skull so as to permit the slight dislodgement of the meten. and epen. 

 and divide the NN. auditorius and facialis ; this will allow the 

 small Lobus appendicularis to leave its fossa. Cut the N. abdu- 

 cens and the N. trigeminus, with the tracer and scissors dislodge 

 the hypophysis, and cut the N. oplicus. Lastly, divide the NN. 

 trochlearis and ocuiomotorius. 



