47 



Note the distribution of the vessels in the muscular tissue, the 

 shape of the capillary network, and compare it with 88. 



90. Capillaries of an organ. Demonstration. 

 Blood vessels injected with carmine gelatin mass ; hardened in 

 alcohol ; collodion. 



Note the capillary network and the great vascularity. The 

 vascularity of the different organs will be considered subsequently 

 with the organs themselves. 



LYMPHATIC TISSUES. 



91. Payer's patch. Cat. Trahsection of the ileum, vom 

 Rath's fluid ; collodion ; sections ;u. Stain with hematoxylin 

 15 minutes, picrofuchsin 15 seconds. 



The section passes through a Peyer's patch. In the villi and 

 mucosa will be found diffuse adenoid (lymphatic) tissue. Peyer's 

 patch is an aggregation of lymphatic nodules, "dense" lymphatic 

 tissue. Note carefully the general structural appearance of adenoid 

 tissue, the character of the lymph cells and their nuclei. Can you 

 recognize the lymphoid reticulum ? Does the preparation show the 

 relation of the lymphatic tissue to the epithelium ? 



92. Tonsil. Dog. Section of the tonsil. Zenker's fluid ; 

 paraffin ; sections fjL. Stain the section with hematoxylin 30 

 minutes, picrofuchsin 30 seconds. 



Study the preparation, recognizing that it is composed of ade- 

 noid tissue, consisting of nodules surrounded by diffuse adenoid 

 tissue. Identify its structure with that of Peyer's patch. Note the 

 relation of the lymphatic tissue to the overlying stratified epithelium 

 of the oral cavity ; is the epithelium destroyed or filled with lymph 

 cells ; are there any lymph cells upon the surface of the epithelium ? 



93. Lymphatic gland. Cat. Transection, vom Rath's fluid ; 

 stained in toto in paracarmine ; collodion ; sections )x. Mount 

 directly. 



Study the general structural appearance of the gland. Identify 

 the following regions or parts : (a) the cortex, medulla and the 

 hilum ; {b) the lymphatic nodules (follicles) in the cortex ; (c) the 

 capsule and the trabeculae ; can you find plain muscle in the cor- 

 tex ? (a?) blood vessels. Compare the lymphatic gland with 91 

 and 92. Can you recognize the lymph sinuses bordering the trabe- 



