126 



sam, the paraffin may easily be washed away, at first with 

 spirit, and afterwards with water, and the section stained, 

 mounted in glycerine, &c., &c. There really is very little 

 difficulty in getting rid of the paraffin, excejit where it has 

 run into internal cavities. 



If balsam-mounting be adopted, there is no difficulty at 

 all. Coming directly after the spirit, a drop of creosote 

 (common creosote, not carbolic acid, tlie odd ingredients of 

 the former rendering it far more useful than the latter) clears 

 the section up at once, and a few washings with turpentine 

 gets rid of all the paraffin, and leaves the tissue quite ready 

 for the balsam. 



It is by no means necessary, as Strieker recommends, to 

 apply the creosote and turpentine before imbedding. With 

 care the cavities and spaces between the paraffin and the 

 object may be reduced to a minimum; and even when they 

 are formed, it is quite possible, in spite of them, to get excel- 

 lent sections. 



Nor need the method be necessarily limited to objects 

 hardened in chromic acid or preserved in spirit. It is most 

 useful with them, but may be employed without the inter- 

 vention of any alcohol at all. Care, however, must then 

 be taken to remove as much moisture as possible from the 

 surface of the object, and to select a paraffin mixture of 

 suitable firmness. 



There is an incidental advantage of this imbedding pro- 

 cess. An object may be imbedded, several sections made, 

 and remainder of the cake replaced in spirit, in which, with 

 a sufficiently instructive label, it may be preserved for any 

 length of time, ready for other sections to be cut whenever 

 they may be wanted. 



7%e Grey Matter of the Cerebral Convolutions. 

 By Professor Cleland, of Galway. 



(With Plate VII). 



The microscopy of the grey matter of the cerebral hemi- 

 spheres is a subject which has occupied in recent years the 

 attention of numerous observers; but the accounts of differ- 

 ent writers are sadly conflicting, and the layers which they 

 describe are so variously and even arbitrarily enumerated, 

 that it is difficult to compare their descriptions in detail. 



