DIRECTIONS FOB LABORATORY WORK 791 



tics of lymph, hemal and hemolymph nodes? Blood and lymph supply 

 of each? Giant cells? 



(2) TONSILS (Faucial tonsil}. Study a stained section of the faucial 

 tonsil. Make h.p. sketch (191) of the infiltrated stratified squamous 

 epithelium lining a crypt. Function of tonsils? 



(3) SPLEEN (Lien). (a) Study a stained section of spleen. Note 

 (1) robust fibromuscular capsule ; (2) similar trabecula? ; and (3) splenic 

 (Malpighian) corpuscles with central or subcentral arteriole. Sketch 

 segment under l.p. (192). Study under h.p. the spleen pulp, noting dif- 

 ference between pulp cords and intercordal pulp (venous sinuses). Sketch 

 (193) a small area of this portion of the parenchyma, noting types of 

 cells and character of the terminal arterioles. Study injected specimen 

 of spleen, noting vascular terminals within the lobule. 



(b) From a. smear preparation of spleen, stained with Wright's 

 blood stain, sketch (194) the several types of parenchymal cells: (1) 

 lymphocytes; (2) polymorphonuclear neutrophil leucocytes; (3) large 

 mononuclear leucocytes ('splenic cells') ; (4) eosinophil leucocytes; (5) 

 basophil leucocytes; (6) erythrophages ; (7) erythroblast ; (8) giant 

 cells. Make similar study of an aceto-carmin preparation mounted in 

 glycerin. What are the chief criteria for distinguishing the several 

 lymphoid organs from lymph glands, and from each other? Functi<*n 

 of spleen? 



XII. SKIN AND APPENDAGES 



(A) THE SKIN (Integument). 



(1) Study under l.p. a vertical stained section of thick skin (from 

 palm of hand or sole of foot). Note epidermis (cuticle), dermis (cor- 

 ium, cutis), and the tela subcutanea. Distinguish between the stratum 

 corneum and the stratum germinativum ; between the pars papillare and 

 the pars reticulare. Note the spiral epidermal portion of the ducts of 

 the sweat glands. Note also the panniculus adiposus of the subcu- 

 taneous tissue. Sketch a narrow segment through entire thickness 

 (195). Make h.p. sketch (196) of several adjacent cells from each of 

 the six distinct layers of the epidermis. What are the several factors 

 (physical, chemical and mechanical) which operate upon a cell of the 

 cylindrical cell layer during its metamorphosis into an element of the 

 scaly cell layer? 



(2) Study under l.p. a vertical stained section of thin skin (e.g., 

 from abdomen). Sketch (197). What are the chief structural differ- 



