EXPERIMENTAL EQUIPMENT AND PROCEDURES 



Operations are performed in dishes described above. Following the operation, when the 

 transplant has "taken", the embryo may be transferred to a covered stender, the bottom 

 of which has a thin layer of 4-5% agar. This provides a softer base than glass so that 

 there is less danger of injury. Such operated animals should be kept at constant temper- 

 ature toward the lower levels of tolerance for the particular species under investigation. 



EXTR4 FINGE« BOWLS 



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 STENOERS 



EXTRA OPERATING DISHES 



EXPERIMENTAL EMBRYOS -^ 



CONTROL EMBRYOS -». 



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RING STAND 



HOLTFRETERS SPRING WATER Al£OMOL 



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CONC, 20 % 



MICROSCOPE LAMP 



NEEDLE a HAIR LOOP BOARD 



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WASTE FINGER BOWL 



OPERATING BOARD 



METAL BOX WITH DRAWERS 

 FOR INSTRUMENTS 



BINOCULAR MICROSCOPE 



PLAN FOR OPERATING TABLE 



ASEPSIS 



The amphibian embryo is relatively immune to infection, or bacterial contamination. 

 Operated embryos are, of course, exposed to such conditions but the wounds heal so 

 rapidly that simple aseptic precautions are generally sufficient to protect the embryo. 



In recent years Detwiler, Copenhaver, and Robinson (1947) have demonstrated that 

 sodium sulfadiazine (0. 5%) in any of the various operating or culture media is perfectly 

 harmless to the embryo, and will reduce the operative casualties on the central nervous 

 system from 95% to 5%. The sulfadiazine may partially crystallize out, but these crys- 

 tals are harmless except as they may mechanically pierce the ectoderm of the embryo. 



At later larval stages, or just after metamorphosis, amphibia may become susceptible 

 to fungus or other skin infections. These can be treated locally with dilute mercuro- 

 chrome, neo-silvol, or very concentrated salt solutions painted onto the affected area. 

 Generally a copper penny in the same tank will keep down all fungus. 



