CUTTING SECTIONS OF FROZEN TISSUE. 25 



ring for the cord and the variable stop L were suggested by H. E. Durham 

 (Proceedings Physiol. Soc., Jl. Physiol., Vol. xix., p. xvi.). The movable 

 carrier also permits different parts of the razor to be used and the ring 

 enables one to fix the rocking arm in any position without danger of 

 its slipping. 



Freezing- and cutting 1 in gum mucilage. 1 Crystalline sugar 

 1 oz. in 1 fl. oz. water, gum mucilage (1 Ib. gum accacia to 8 fl. oz. 

 water) 5 oz., water 9 oz. Mix, filter, and add thymol or carbolic 



FIG. 10. Williams' Ether Freezing Microtome. (Made by Swift). 



P Metal cap upon which the tissue is placed, fixed by a vulcanite collar in the 

 glazed platform, which is supported by a pillar clamped to the table. S Atomiser 

 actuated through F by a foot blower. E Ether bottle. C Wooden cap to cover the 

 tissue whilst it is being frozen. The knife sledge is supported upon screws A for 

 lowering the razor after each cut, aa, for levelling the edge of the razor. Two vertical 

 screws bb, for adjusting its slope and two horizontal ones for fixing it in position. 



1 The method of freezing by means of ice and salt was introduced into histology 

 by Prof. W. Rutherford in 187*2, Dr. I". Prit chard suggesting the use of gum for 

 embedding, to which Dr. D. J. Hamilton (then of Edinburgh) subsequently made the 

 addition of syrup to prevent crystalisation. Mr. Bevjin Lewis. West Riding Asylum, 

 introduced ether as a means of freezing in 187r>. 



