GENERAL BIOLOGY 



(upper arm), antebrachium (fore arm), manus (hand) ; the latter 

 with four digits, the innermost of which bears a swollen cushion 

 in the male. 



2. The much longer posterior pair each divided into three re- 

 gions, femur (thigh), crus (shank), pes (foot), the latter with 

 five long digits connected by a web. There is a large firm promi- 

 nence on the inner side of the ankle; callosites are found under 

 the joints of both pes and manus. 



Draw entire frog and label parts named above. 



II. INTERNAL CHARACTERS. 



i. GENERAL. 



a. Place the frog under a bell-jar with a sponge saturated with 

 chloroform; when dead pin out under water on its back. 



b. Cut through the skin along the median ventral line from the 

 posterior end to the jaw (raising the skin from the body and not 

 cutting deep) ; cut transversely at each end of first cut and turn 

 aside the two large flaps thus made. 



c. On the flap of skin on each side is seen a large vein near 

 the shoulder, the musculo'-cutaneous vein. The muscular walls of 

 the abdomen are covered by a thin, shining connective tissue, 

 sheath, the eponeurosis, through which in the median region is 

 seen the rachis abdominis passing from the pelvis to the sternum 

 and somewhat divided by transverse lines into segments or 

 myotomes. Through this muscle is seen the dark blood of the an- 

 terior abdominal vein in the median line. 



d. With a pair of forceps raise the body wall and carefully cut 

 it through by a slit to the right of the median line ; continue this 

 cut from pelvis to sternum and make transverse cuts as in the 

 skin so as to throw back a flap of body wall on each side; the left 

 one should show the anterior abdominal vein on its exposed sur- 

 face. 



e. With forceps raise the sternum and carefully cut off the 

 fibrous bands seen passing to soft organs dorsal to it ; with strong 

 scissors cut through the sternum and other hard parts on the 

 median line carefully holding it up away from the soft parts dorsal 

 to it. Turn each half outward and pin firmly; pin the anterior 

 limbs out at full length. 



f. The liver is conspicuous, forming a large brown mass with 

 the pericardial sac just anterior to it. 



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