How To Study Living Animals


5. Development of the Chick
Materials.

An incubator, a brooder, a setting of eggs herunterladen.

Directions.

Read carefully the directions for setting up and regulating the incubator. Remember that the temperature should average 103 degrees and should not vary more than two or three degrees above or below this herunterladen. Candle the eggs from time to time and note difference in appearance, as development proceeds, especially as to transparency and size of the air space microsoft office kostenlos downloaden vollversion deutsch chip. An egg that is transparent after ten days is probably infertile and should be removed. Eggs which are developing properly will show from this time on a well developed air space, and will be quite opaque. The veins often give a spider-web appearance.

Twice each day remove the tray of eggs and allow to cool slightly. Once a day the eggs should be turned before the tray is returned to the incubator.

Questions.

1. Describe the appearance of the shell when the chick is about to come out. In about how many days after you put the eggs in the incubator did you first note this change? You should watch the incubator carefully from the eighteenth day on.

2. What proportion of the eggs hatched? What reasons can you suggest for the failure of some to hatch? Did any which were pipped fail to hatch? If so, break them open and see if you can discover the trouble.

3. How does the chick get out of the shell? How long does it take for it to get out after the shell is chipped? How does a chick look as soon as it has come out of the shell?

4. With what is a chick covered when it is first hatched? How long before feathers begin to develop?

5. How long before a chick needs food? How does it recognize it?

Summary.

1. What are the two kinds of development?

2. What are the stages in embryonic development?

3. What two general types of postembryonic development as determined by the amount of the food supplied in the egg?

C. Protection and Care of Young