SECTION CUTTING. 



Begin with simple tissues, reserving intricate detail until a short 

 period of practice gives the technique needed. I do not recommend 

 the camera lucida, as my experience strongly impresses me with this 

 as a fact, that he who cannot sketch without a camera will never 

 sketch with one. Pencil drawings may be very effectively colored 

 with our staining fluids, diluted if necessary. 



PREPARATIONS OF TISSUES EOR MICROSCOPICAL 



PURPOSES. 



TISSUES ARE STUDIED BY TRANSMITTED LIGHT. 



The microscopical study of both normal and pathological tissues is 

 invariably conducted by the aid of transmitted light. 



Tissues, if not naturally of sufficient delicacy to transmit light, 

 must in some way be made translucent. 



Delicate tissues like omenta, desquamating epithelia, fluids con- 

 taining morphological elements, certain fibres, etc., are sufficiently 

 diaphanous, and require no preparation. Such objects are simply 

 placed upon the glass slip, a drop of som'e liquid added, and, when 

 protected by a thin covering glass, are ready for the stage of the 

 microscope. 



PREPARATION BY TEASING. 



The elements of structures mainly fibrous, e. g., muscle, nerve, 

 ligament, etc., are well studied after a process of separation, by 

 means of needles, known as teasing. A minute fragment of the organ 

 or part having been isolated by the knife or scissors is placed upon a 

 glass slip, and a drop of some fluid which will not alter the tissue 

 added. Stout sewing needles, stuck in slender wood handles, are 

 commonly employed in the teasing process. The separation of tissues 

 is frequently facilitated by means of dissociating fluids which remove 

 the cement substance. fi 



SECTION CUTTING. 



After having become familiar with the various elementary struc- 

 tures of animal tissues, we proceed to the study of their relation to 

 organs. 



As the teasing process is not available with such complicated 

 structures as lung, liver, kidney, brain, etc., we resort to methods of 

 slicing, i. e., section cutting. 



Sections must be made of extreme tenuity, in order that the natu- 



