APPENDIX 



The supplies for each student required to complete the direc- 

 tions in this manual are: 



One injected frog (preferably doubly injected). 



One frog, which need not be injected. 



One mounted skeleton of frog. This is desirable but not 

 indispensable. 



Seven histological slides, including one each of the following: 

 blood smear; section of hyaline cartilage; transverse 

 section of decalcified femur; longitudinal section of 

 striated muscle; transverse section of sciatic nerve; sec- 

 tion of skin; transverse section of ileum. 



One set, ten stages in the development of the frog. 



One bullfrog tadpole. 



All these may be readily obtained from any of the biological 

 supply stores. The following suggestions may be of service to 

 the teacher who prefers to prepare his own material. 



The best time to collect the frogs is at night and during the 

 breeding season, in the Spring, when they can easily be netted 

 with the aid of a lantern or electric torch. 



They may be kept in large tanks with from one to two inches 

 of water at the bottom, which should be changed frequently. 

 Overcrowding the tanks should be avoided. Frogs need not be 

 fed during the winter months if kept in a cool place. If feeding 

 is to be demonstrated, it should be remembered that the frog 

 will take only moving food. 



The best method of killing the frogs is by the fumes of ether. 

 When the tissues are to be preserved for microscopic preparation, 

 the preferable method is that of "pithing." Locate with the finger- 

 nail the point at which the skull joins the vertebral column, press 

 the head down sharply and make a narrow, deep, transverse in- 

 cision at the point located. This severs the spinal cord, and if 

 done neatly, results in practically no loss of blood. 



To preserve the frogs, use formaldehyde in 5% aqueous solution. 

 The commercial formaldehyde is 40% formalin. Mix 5 parts of 



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