THE GARDEN TOAD 7 



line an opening. This is the anal opening or amis. Note 

 the general make-up of the toad. How do its arms com- 

 pare with our own ? How do its fore feet (hands) differ 

 from its hind feet ? Note that the body is covered by a 

 tough enveloping membrane, the skin. In the skin are 

 many glands which by their excretion keep it soft and 

 moist. 



Internal structure TECHNICAL NOTE. With a fine pair of 

 scissors make a longitudinal median cut through the skin of the 

 venter from the anal opening to the angle of the lower jaw. Spread 

 the cut edges apart and pin back in the dissecting-pan. 



Note the complex system of muscles which govern the 

 movements of the tongue. Observe a number of pairs of 

 muscles overlying the bones which support the arms. 

 These are attached to the pectoral or shoulder -girdle. 

 Note the large sheet of muscles covering the ventral 

 aspect of the toad. These are the abdominal muscle 's, 

 which consist of two sets, an outer and an inner layer. 

 Note that posteriorly the abdominal muscles are attached 

 to a bone. This is the pubic bone of the pelvic girdle 

 which supports the hind legs. 



TECHNICAL NOTE. With the scissors cut through the muscles of 

 the body wall at the pubic bone and pass the points forward to the 

 shoulder-girdle. Separate the bones of the shoulder-girdle and pin 

 out the flaps of skin and muscle to right and left in the dissecting- 

 pan (see fig. i). Cover the dissection with clear water or weak 

 alcohol. 



Note two large conspicuous soft brown lobes of tissue. 

 These form the liver, an organ which produces a secretion 

 that assists in the process of digestion. Note just anterior 

 to the liver and extending between its two lobes a pear 

 shaped organ, the heart, which may yet be pulsating. 

 Are these pulsations regular ? How many occur in a 

 minute ? The lower end or apex of the heart, ventricle, 

 undergoes a contraction, forcing blood out into the blood- 



