BIOLOGY EXPERIMENTS CHILDREN

(Jacob Rumans) #1

Examinetheopenedshellandthecontentsof the egg withyourhandlens.
Examinethe unlaid yolks too.
You will observe:Theunlaid chickeneggs resembleclusters ofyeIlow-
orangegrapesofdifferentsizes.


The shellofthe whole egg has thefamiliarhardoutersurfacewhichyou
have seen inothershells,butthere is a thin,tissue-paperymembraneclinging
to its innersurface. There is a space between the thin membraneandthe
hardshell at the roundedendofthe egg,butat allotherplaces the papery
membranesticks close to the shell.
Now, look at the egg in the dish. Youwill see thefamiliarorangeyolk
in the middlesurroundedby the thick, loose "white"ofthe egg. Youwill
see a whitespotjustaboutin the middleofthe yolk.
Lookhard at two ends of the yolk opposite each other;you will see
twisted threadsofwhite, similar to butthicker thanthe white spot in the
middleofthe yolk. Aroundthis is the thick whiteofthe egg.

Theclusterofunlaidegg yolks wastakenfrom thechickenby thebutcher
beforethe eggs were laid. These, ofcourse, are egg yolks.
The white spotin each yolk is the egg nucleus from which a newbaby
chickmighthave developedif the egg had been fertilized by arooster.Eggs
areproducedin apairofovaries in the bodyofthemotherhen.
The yolksurroundingthe nucleusprovidesa supplyoffood for adevelop-
ing babychick. Of course, egg yolks are nourishingfood for humans,too.
The white of the egg serves as protection,while the two twisted white
cordsyou saw on the yolk keep itattachedto the shell. They act ashammock
stringsfor the developingbaby chick.
The paperymembraneunderthe brittleoutershell is alsoprotective. It
is thinenoughsothatair can passthroughfor thedevelopingbabychick. The
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