408 TECHNICAL AND OPERATING EQUIPMENT 



2 fine pipettes (inside diameter 1 mm. ) 

 12 regular medicine droppers 

 6 shell depression slides 



1/2 oz. round cover glasses, #1 thickness (to cover depression) 

 1 small glass tumbler, cotton in bottom and partially filled with 70% alcohol for 



sterilization of operating instruments. 

 Absorbent cotton 



Operating equipment: 



1 hack-saw with extra blades (ampoule saw may be satisfactory) 



2 watchmaker's forceps, §5 



1 pair regulation forceps 



2 steel needles, ground to fine points 

 1 pair coarse scissors (large) 



1 pair fine scissors (small) 



PREPARATION OF EQUIPMENT 



All glassware and instruments should be thoroughly washed in non-caustic soapy water; 

 rinsed in hot, running tap water; and put aside to dry on a clean cloth towel. The metal 

 instruments and culture dishes may be further sterilized in the dry sterilizing oven while 

 the solutions should be autoclaved at 1 5 pounds for at least 15 minutes. Thereafter the 

 operating equipment may be kept in 70% alcohol to which a drop of iodine solution has 

 been added. The greatest source of bacterial or mold infection is not from such pre- 

 sterilized equipment but rather from the hands and breath of the operator. One should 

 work in a draft-free room, away from windows, and the embryos should be exposed to 

 the air only when absolutely necessary. 



PRELIMINARY SUGGESTIONS 



1. Become re-acquainted with the normal morphogenesis of the chick egg. (Hamilton's 

 Lillie, 1952 and pages 410, 411, 413) 



2. Select eggs that are uniform in size, shape, and color for any one experiment. 



3. Check the incubator temperature and humidity at least once each day. Temperatures 

 above 103° F. are more deleterious than below that level. 



4. Remember that genetic factors may contribute to high mortality. It cannot be stressed 

 too frequently that one must become thoroughly acquainted with the source of the eggs 

 being used. 



5. Do not wash or submerge the eggs for long in water because the embryo normally 

 breathes air through its porous shell. Washing will remove a thin surface cuticle 

 which protects the chick embryo against the invasion of microorganisms. Prior to 

 operations within the egg, sterilization of the shell and exposed shell membrane may 

 be accomplished with a cotton swab soaked in 70% alcohol, 1% iodine in alcohol, or 

 chlorazene. The chlorazene is made up by adding 3 tablets to a quart of warm water. 



6. The membranes should be observed just prior to the time for hatching. When the 

 extra-embryonic circulation begins to regress, the incubation temperature can be 

 lowered and the humidity raised. Should the chick's beak happen to lie beneath the 

 artificial window, this window should be removed on the 19th or 20th day. Frequently 

 operated chicks must be assisted in the hatching process on the 21st day. Do not 

 attempt to remove the chick until the yolk sac is completely retracted into the chick 

 mid-gut. 



