Journal of 



Applied Microscopy. 



Volume II. FEBRUARY, 1899. Number 2 



General Methods in Botanical Microtechnique. 



II. 



7.— CUTTING SECTIONS. 



The sections must be cut on a microtome. Cut one of the objects with a 

 suitable amount of paraffin out of the cake by means of a sharp scalpel, taking 

 care that the edges of the block will be parallel with the general contour of the 

 object. Trim the block down to a rectangular shape and fasten it to a block of 

 wood, or a special holder which goes with some microtomes. Before attempt- 

 ing to fasten the block to the holder, have the top of this covered with a cushion 

 of paraffin. The paraffin block must be fastened firmly, and the edges especially 

 sealed with a hot needle so that there will be no danger of having it come off. 

 After having cooled off the block in cold water and trimmed the sides to be 

 parallel, fasten it into the clamp of the microtome and adjust the knife and 

 clamp so that the knife will strike the paraffin block perfectly parallel. The 

 ribbon of sections should be straight and, not coiled. If the ribbon coils, no 

 good mounts can be made even if everything else has been satisfactory so far. 

 The desirable thickness of the sections depends somewhat on the nature of the 

 material and the object to be attained. As a general rule most sections may be 

 cut ten microns (/u) thick. The section knife or razor must be sharp and clean, 

 with no trace of the smallest notches, at least in that part with which the cutting 

 is done. It is well to examine the edge of the knife under the low power of the 

 microscope to see that it is in good condition. After the ribbon has been cut 

 care should be taken to have all the pieces arranged in a continuous series, from 

 left to right, on a clean sheet of paper. The sections may be covered with a 

 wide bell jar. If the sections do not hold together well while cutting, the par- 

 affin may be too cold or there may be other defects. These should be discovered 

 and removed before proceeding further. Ribbons should be cut yards in length, 

 without a single break, when serial sections are cut. 



8.— MOUNTING. 



1. Take a clean slide and put a small drop of albumen fixative on it. 

 Spread it out over the surface with the finger into a very thin, even layer, being 

 careful that no part of the finger touches the slide before being covered with a 

 layer of the albumen. The layer must be quite thin so that you can just leave a 



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