XIV 



VERTEBRATE ANATOMY 



(Readings: Weisz, pp. 201-223; also browse through Chapters 12, 13, 14, 20 

 and 21, looking especially at the diagrams and photographs. S. P. T., pp. 1 17- 

 158, and browse through to p. 220. Villee, pp. 234-242, and browse through 

 Chapters 17-25.) 



Our first semester in the laboratory was de- 

 voted primarily to the forms and activities of in- 

 dividual cells. We stressed mainly widespread or 

 universal similarities among cells, whether ani- 

 mal, plant, or protist. 



This semester we will study the aggregations of 

 cells which compose the tissues and organs of the 

 higher organisms. A tissue is a group of cells 

 which display common functional and/or mor- 

 phological properties. Usually in a tissue the 

 cells are bound together to form sheets, layers, or 

 more-or-less solid structures; but this need not 

 always be so. The circulating blood cells in 

 vertebrates, for example, constitute a tissue. The 

 higher animals are composed mainly of four 

 types of tissue: epithelial, connective, muscular, 

 and nervous. Higher plants also possess four 

 primary types of tissue (protective, meristematic, 

 "fundamental," and conductive or vascular). An 

 organ is a structure composed of two or more 

 tissues that performs a specialized function. 



Just as we started last semester by surveying 

 types of cells, the first two laboratory sessions 

 this semester will be devoted to studying a few 

 typical higher organisms. In this first period we 

 shall study vertebrate anatomy; next week we 

 will examine the anatomy of higher plants. 



The work this week may be done in pairs, one 

 partner dissecting a rat, the other a frog. As you 

 dissect, compare the similarities and differences 

 between these vertebrates. Learn the names, 

 locations, appearance, and functions of the 

 various organs you encounter. Your textbook 

 will help, as also will wall charts posted in the 

 laboratory. You and your partner should try 

 to dissect in the same body area at the same 

 time. 



A systematic procedure, outlined below, will 

 direct you to the major structures. Strike out on 

 your own, if you like; but if you do, plan ahead 

 how you are going to go about it. 



When you have finished examining an organ, 

 it is often helpful to remove it. If you choose to 

 do this as you go along, slice into each structure 

 you remove. Note its internal appearance, 

 whether it is solid or possesses a cavity, and 

 whether it appears homogeneous or differenti- 

 ated into distinct regions. Keep your animal and 

 the organs you have removed from it moist, and 

 they will retain their natural shape and appear- 

 ance throughout the period. 



Stained sections of the major organs will 

 probably be available from your instructor. 

 Although this will be a good time to look at them. 



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