68 



lobules which are surrounded by fibrous tissue, from which 

 septa pass into the lobules and divide them into secondary 

 lobules. The secondary lobules are composed of adenoid 

 tissue. This is denser and stains more deeply in the per- 

 iphery of the lobules forming the cortical zone; the less 

 dense center forms the medullary portion. In the medul- 

 lary portion are found the concentric corpuscles of Hassall. 

 They are the remains of the entodermal epithelial tissue of 

 which the gland was composed in its early development. 



(d) Compound Lymph Gland. 



A tyinph gland was hardened in mercuric chloride, stained in 

 Delafield's hsematoxylin, embedded in paraffin, and sectioned. S^c- 

 tions were fixed to cover glasses, counter-stained in eosin, dehy- 

 drated, and cleared in oil of ber^amot and xylol. Mount on a drop 

 of balsam. 



Examine first under low power. Observe the capsule, 

 from which trabeculse pass into the gland, dividing its outer 

 or cortical portion into comparatively large compartments, 

 in which the cortical nodules of adenoid tissue are found. 

 On entering the medulla the trabecula? divide and anasto- 

 mose ; the network so formed has small meshes in which 

 are found the medullary cylinders of adenoid tissue. The 

 adenoid tissue is composed of a reticular framework and 

 cells. 



" The cortical follicles and the medullary cylinders do 

 not completely fill out the compartments made for them 

 b\ r the capsule and trabecula3 respectively, but a narrow per- 

 ipheral zone of each compartment is left free, this is a 

 lymph sinus." (Klein.) The lymph sinuses form an anas- 

 tomosing system. Sketch a portion of the gland under low 

 power. 



(e) Reticulum of Adenoid Tissue. 



A lymph gland was hardened in alcohol, and cut on the freez- 

 ing microtome. The sections were stained in Boehmer's hsematoxy- 

 lin. They were then transferred to a test-tube half full of distilled 

 water, in which they were carefully shaken for 10 or 15 minutes. In 

 this way many of the lymph cells are shaken out of the reticulum. 

 Mount in gum gtycerine. 



Examine under high power, using one of the smaller 

 openings in the diaphragm. A reticulum of very fine 



