524 Transactions of the Society. 



razor now passed over the latter cuts off a section of the same 

 thickness. By turning the cap through half an interval, sections 

 of half that thickness may be obtained. To fix the specimen it is 

 only necessary to fill the cylinder with ice and salt, the specimen 

 being previously prepared in gum, according to the general rule 

 when freezing is employed as the means of imbedding. 



The form in which ether is the freezing agent employed 

 (fig. 84) differs mainly in the fact, that the lower half of the cylinder 

 is a chamber for holding the ether, with the two nozzles that give 

 the necessary jet. The freezing plate, cap, and regulating apparatus 

 are the same as in the ice and salt machine. Mr. Swift (to whose 

 skill and ingenuity the details of manufacture are due) has intro- 

 duced a very ingenious but yet simple means whereby some of the 

 ether can be saved from the spray ; much must of course escape, 

 but much also falls back on to the jets again (since the spray is 

 a vertical one) ; this portion impinges on to a funnel-shaped 

 diaphragm, which acts as a lid to the ether chamber, and through 

 which, by means of a minute opening, it again finds its way back 

 to the ether chamber. 



For those who, like myself, have to work for a large histo- 

 logical class, there is nothing equal to the Groves- Williams ether 

 microtome in the laboratory : but for intermittent and home work ' 

 I believe that the form of instrument that I present to-night, 

 leaves scarcely anything to be desired in accuracy of work, simplicity, 

 convenience, and portability. 



