42 ELEMENTS OF COMPARATIVE ZOOLOGY. 



reproductive organs and kidneys. These will differ in 

 their appearance in the two sexes. 



In the male a yellowish, rounded body (testis) occurs on 

 either side of the median line, and just in front of each 

 are the yellowish, lobulated fat-bodies. Beneath (dorsal to) 

 the testes are the reddish -brown kidneys, each having on 

 its ventral surface a yellowish or golden adrenal. 



What is the shape of the kidneys ? Are the testes and 

 kidneys connected in any way ? Do you find the ducts 

 (ureters) leading back from the kidneys ? Where do they 

 end? 



In the female, the ovaries, crowded with dark-colored 

 eggs, occur in the place of the testes, their size depending 

 upon the season. Near them are the coiled oviducts. 

 Trace these forward and back to their terminations. Do 

 you find the fat-bodies ? Do kidneys and adrenals corre- 

 spond to the conditions described for the male ? Are these 

 ureters distinct from the oviducts ? Draw the reproductive 

 and urinary organs of your specimen. 



Insert a blowpipe in the glottis (p. 40) and inflate the 

 lungs. What is their shape ? Are they made up of little 

 chambers (air-cells) throughout ? 



Between lungs and liver is the pericardial cavity, and 

 through its walls in the freshly killed specimen the beating 

 of the heart can be seen. Open the pericardium very care- 

 fully and expose the heart; make out the ventricle behind, 

 and the auricles in front. Arising from the ventricle and 

 crossing the auricles is the arterial trunk. Carefully clean 

 this from the surrounding tissues and trace* it to its 



* This is best done in an injected specimen. The injection can be 

 made by opening the ventricle and through it inserting the canula 

 into the arterial trunk and tying it there. Then force in the in- 

 jecting fluid. 



