82 



VI. THE EPIDERMIS STOMATA. 



can be packed together without other support than they give 

 to each other. The elder or sunflower pith necessary for this 

 purpose is obtained from dried pieces of the stems of those plants 

 by stripping off the cortex and ring of woody tissue. A piece of 

 pith about an inch long is cut in two lengthwise with a sharp 

 razor. The flat strip of leaf which has to be cut is now laid 

 between the two halves of the pith, so that the end of the strip 

 reaches to the end of the split piece of pith. Thin cross-sections 

 are then taken through pith and object at the same time, and 

 the sections are lifted with a camel-hair brush from the blade of 

 the razor on to the object-slide. While cutting, the two pieces 

 of pith can either be held together simply with the fingers, or the 

 two halves can be fastened together by winding round them a 

 piece of thread. In cutting, the pith is so held that the razor 

 passes through the strip of leaf from side to side and not from 

 edge to edge ; in this way many approximately equal sections 

 can be taken. For delicate objects the softer sunflower pith is 

 preferable to the somewhat harder elder pith ; for more resistant 

 objects, like that in question, elder pith is better used ; for still 

 more resistant objects, not pith, but fine cork, as used for bottles. 

 The preparation of sufficiently thin sections will probably offer 

 no insuperable difficulties, but may be ensured by the use of a 



hand microtome, such as 

 is illustrated in the an- 

 nexed Fig. 29 (Leitz, Wetz- 

 lar, 15s.). The object to 

 be cut is placed in the tube, 

 fixed by the clamping 

 screw, and adjusted level 

 with the glass cutting 

 table. The adjustment 

 of the object before and 

 after cutting is effected 

 by means of the screw 

 bottom, one division on 

 the graduated tube of 

 which indicates T ^ mm. 

 (asVo inch )- Cutting is 

 performed by a razor, the blade of which is pressed flat on the 

 glass cutting table. An ordinary razor can be used, or, better, 

 one which is hollow on the upper, flat on its lower side. 



FIG. 29. Leitz's hand microtome. 



