22 



MICROSCOPICAL RESEARCH 



is taken at right angles to the axis of growth. The radial longitudinal 

 section is taken through the axis of growth. The tangential longitudinal 

 section may be varied in its direction between the central axis and the 

 circumference in accordance with position of the special tissti,e it is 

 desired to examine. Each section when placed under the microscope 

 will present to the observer a surface cut at right angles to each other, 

 and without which a complete study of the tissue could not be made. 

 It is, therefore, of the greatest importance that the student should 



Fig. 14. — Photographs of the operator in the act of cutting sections. A, showing the 

 point of the knife in contact with the specimen. B, showing the position of 

 knife at completion Of cut, with the section resting on the blade and the 

 paraffin curled over in front of it. The movement of the cut is a sliding one, 

 its traverse being from right to left, the full length of the blade having been 

 used in the operation. 



thoroughly understand the principle of section-cutting, as on this, more 

 than anything else, depends his success or failure in the production of 

 satisfactory preparations. 



The melting point of the paraffin used for imbedding purposes is 

 130 degs. Fahr. When new it has a tendency to "crumble" when the 



