CuRRAN, A Neiu Association fiber Tract. 647 



If we use a stronger solution the fibers will be firmer for dissection, 

 but the nuclei will become bleached, and there will be no definite line 

 of demarcation to distinguish the gray from the white matter. The 

 brain should remain in situ for a day or two ; this is a sufficient 

 length of time to allow of hardening to such a degree as will enable 

 it to retain its shape. It should then be removed and placed carefully 

 in a 10 per cent solution of formalin for three weeks or a month. I 

 have also obtained good results when the brain was taken out shortly 

 after death and preserved in the above solution without carotid injec- 

 tion. In case of early removal, the fluid has time to penetrate -to the 

 center before softening takes place. 



The only instrument necessary is a blunt pair of forceps which, 

 when closed, are smooth and even at the edges where they meet. When 

 such forceps are closed, they act as a blunt dissector. As well as 

 separating fibers with the forceps thus arranged, it is sometimes 

 necessary to lift bundles out of their places and to pull on them in 

 order to ascertain the direction of their fibers. For this purpose the 

 interlocking ridges should be fine and transverse in direction, to 

 permit of a gentle but firm grip on small l)undles of fibers without 

 the danger of tearing or breaking them. Forceps with a few large 

 sharp teeth at the end should not be used. When museum prepara- 

 tions are being made, a very sharp knife will be of use to cut off 

 ragged ends and to trim the dissection. Too much trimming some- 

 times produces a dissection which, though finely finished, is less 

 instructive than one which has not been trimmed at all. The 

 latter shows the direction of the fibers, and any work that is to be 

 done on it should not be such as would obscure this; otherwise the 

 full value of the work would be lost. 



In developing skill in this method, it is necessary to have an 

 abundance of material at one's disposal. Almost every viewpoint 

 revealed by dissection will be new, and the dissector will often be 

 unwilling to proceed further with the dissection in hand, because in 

 trying to show a deep set of structures he Avill have displayed a new 

 and attractive view of another set, not originally intended, which 

 perhaps lie more superficially than or close to the structures first 

 intended to be shown. . Although it mav be desirable to save this 



