184 PRACTICAL HISTOLOGY. 



stained with nitrate of silver. To find them it is 

 best to immerse the joint in fluid, for by this means 

 they are floated up, and may then be snipped oif 

 and mounted. 



THE LYMPHATIC GLANDS. 



Preparation 14, These are chiefly studied by 

 means of sections. They are hardened in strong 

 spirit, into which they are put immediately after 

 removal from the animal ; in two or three days they 

 are sufficiently firm to cut, but improve if left longer. 

 The lymphatic glands of the dog may be recom- 

 mended for demonstrating the structure of these 

 organs, especially for showing the lymph-sinuses 

 and the cortical nodules. The gland is split after 

 hardening into two equal parts by a longitudinal 

 cut through the hilus, and one of these halves is 

 embedded in wax-mass in the usual way (pp. 143, 

 144), and with the artificial surface near one end of 

 the wax cake. The sections, which must be very 

 thin indeed, and should include both cortical and 

 medullary substance, are transferred from the spirit 

 to water, and thence to a slide, and mounted in 

 glycerine, without staining. If the lymph-paths 

 appear filled up with lymph corpuscles, so that the 

 retiform tissue which traverses them is not well seen, 

 but the whole section appears more or less uniform 

 in structure, these corpuscles may often be in great 

 measure removed by vigorously shaking up the 

 sections with water in a test tube, or by gently 

 brushing them under spirit with a soft camel-hair 

 pencil. Unfortunately both these methods tend to 

 break up the sections, and indeed it is not necessary 

 to employ them, if the sections are made sufficiently 

 thin. 



These organs are amongst the most difficult to 

 demonstrate the structure of satisfactorily, so that it 

 may be well to defer their preparation until some 

 practice has been obtained in making sections of 

 other parts. 



