1887-88.] and Embedding Microtome. 1 9 1 



2. Take a piece of the tissue to be cut, of about a quarter of an incli in 

 thickness, and press it into the gum. 



3. Fill the ether bottle with anhydrous methylated ether, and push the 

 spray points into their socket. All spirit must, of course, have been previ- 

 ously removed by soaking for a night in water. The tissue should after- 

 wards be soaked in gum for a like time before being cut. 



4. Work the spray -bellows briskly until the gum begins to freeze ; after 

 this, work more gently. Be always careful to brush off the frozen vapour 

 which, in a moist atmosphere, may collect below the zinc plate. If the 

 ether should tend to collect in drops below the plate, work the bellows 

 slower. 



5. Raise the tissue by turning the milled head, and cut by sliding the 

 knife along the glass plates. 



6. After use, be careful to wipe the whole instrument clean. 



7. Should the ether point become choked, clear by means of the fine wire 

 which is sent with the instrument. 



8. The instrument is intended for use with methylated sulphuric ether. 



9. In clamping the instrument to a table or other support, care should 

 be taken that the zinc plate is in a horizontal position. If the plate be not 

 horizontal, the gum will tend to run to one side. 



The following are the dh'ections for embedding in paraffin : — 



1. Pieces of tissue, or other objects to be cut, should be freed from water ; 

 this may be effected by dipping an object to be embedded into spirit, and 

 then allowing it to dry. 



2. The dried object should be dipped for a moment into melted paraffin 

 which is only slightly heated above its melting-point. 



3. After paraffin has been poured into the metal moulds, and has begun 

 to solidify, the tissue with its adhering layer should be pressed into the 

 cooling paraffin, and held in the position desired till tlie paraffin cools 

 around it. 



4. During the process of " casting " the paraffin blocks, and embedding 

 the objects to be cut, the brass tubes should be placed upon a piece of glass 

 or other substance to which paraffin will not adhere. 



5. When a paraffin block is quite cold, it should be expelled from the 

 brass tube by placing the tube into one of the holes in the wooden rest, 

 and driving it (the block) out by means of the wooden rod. 



6. When the block is placed in the vice which holds it in the well of the 

 instrument, undue pressure should not be applied by the clamping screw ; 

 for if the block be held too tightly, the outer tube will tend to lose its 

 shape. 



7. Full instructions in the methods of embedding both in paraffin and 

 celloidin may be found in the text-books which deal with the methods of 

 Histology. The above directions are only intended to explain a process 

 which may be conveniently followed in using this microtome. 



