144 



Modern Microscopy 



they are then cleared in clove oil and mounted in 

 C. Balsam. 



Heads of frogs, newts, and many other specimens may 

 be infiltrated and embedded in gelatine, but they must all 

 be stained in bulk before they are infiltrated, because the 

 sections must not come in contact with water in any form ; 

 moreover, if the sections were stained the gelatine would be 

 coloured as well as the tissues. 



The Rocking Microtome. This machine is made by the 

 Cambridge Scientific Instrument Company. It is only used 



FIG. 54. ROCKING MICROTOME. 



for specimens infiltrated with paraffin, and it is automatic 

 that is to say, it can be set to cut sections of definite thick- 

 ness, and every time the handle is pulled a section is cut, 

 and the specimen is moved forward ready for another. 



Infiltrate the tissue with paraffin in the ordinary way in 

 a pill-box, and when the paraffin has set, remove the box 

 and trim the paraffin into a rectangular block. Take care 

 to keep the edges quite parallel, so that they may adhere 

 together as the sections are cut and form a riband. The 

 Cambridge Instrument Company make an apparatus for 

 embedding, called embedding L's. If these are used, per- 



