CHAPTER II 

 THE GARDEN TOAD (Bufo lentiginosus) 



LABORATORY EXERCISE 



TECHNICAL NOTE. Although this description is written for the 

 toad it will fit for the dissection of the frog. It will be found, after 

 casting aside a few ungrounded prejudices, that the toad is the 

 better for class dissection. Toads are best collected about dusk, 

 when they can be picked up in almost any garden in town or in the 

 country. During the spring many can be found in the ponds where 

 they are breeding. To kill the toad place it in an air-tight vessel 

 with a piece of cotton or cloth saturated in chloroform or ether. 

 When the toad is dead, wash off the specimen and put in a dissect- 

 ing pan for study. Several specimens should be placed in a nitric 

 acid solution for a day or so (for directions for preparing, see 

 p. 12) to be used later for the study of the nervous system. Also 

 several specimens should be injected for the better study of the 

 circulatory system. With an injecting mass made as directed on 

 p. 451 introduce through a small canula into the ventricle of the 

 heart. This will inject the arterial system, and with increased 

 pressure the injecting mass may be forced through the valves of the 

 heart, thus passing into the auricles and throughout the venous 

 system. After injecting use the specimen fresh or after it has been 

 preserved in 4^ formalin. 



External structure. Note that the body of the toad 

 is divided into several principal regions or parts, as is the 

 human body, namely, a head, upper limbs, trunk, and 

 lower limbs. As you look at the toad note the similarity 

 of the parts on one side to those of the other, as right leg 

 corresponding to left leg, right eye to left eye, etc. This 

 arrangement of the body in similar halves among animals 

 is known as bilateral symmetry. As a rule animals which 

 show bilateral symmetry move in a definite direction. 

 The part that moves forward is the anterior end, while 



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