26 



HUMAN BIOLOGY 



absurd as to wear cotton outer clothing in Northern states during the 

 eight cold months. 



Black clothing absorbs twice, blue almost twice, red and yellow 

 almost one and a half times, as much heat as white clothing (Exp. 10). 

 Which material protects best from radiant heat ? (Exp. 9.) Because 

 large blood vessels are near the surface at the neck, wrists, and ankles 

 very thin or no covering at those points aids greatly in keeping the 

 body cool. High collars, long sleeves, and high shoes are unhealth- 

 ful in warm climates and in summer. What objection to black shoes 

 in summer ? Patent leather ? Show how women dress more sensibly 

 in hot weather than men. 



The kidneys are located on each side of the spinal col- 

 umn in the " small of the back " and extend slightly above 



the level of the waist. 

 They are bean-shaped or- 

 gans about four inches long 

 (Fig. 26). The kidneys of 

 a sheep or ox closely re- 

 semble those of man. They 

 are outside of the perito- 

 neum (Fig. 99) and at- 

 tached to the rear wall of 

 the abdomen. A large 

 artery (12, colored Fig. 5) 

 goes to each kidney and 

 divides into many capilla- 

 ries which surround tubules 

 in the kidneys (Fig. 27). 

 The secretion, containing 

 nitrogenous impurities of 

 the blood, is continually being deposited in the tubules, 

 which take it to a funnel-shaped cavity at the inner edge 

 of the kidney (Fig. 26). From this cavity a white tube 

 called the ureter leads down to a storage organ in the 

 pelvis called the bladder. 



FIG. 26. SECTION OK KIDNEY. 



RA , renal artery ; />, pyramids surrounding 

 hollow space from which the ureter (/) 

 leads the secretion to the bladder. 



