THE CHICK 



Fish, frog, bird, mammal, and man are, for us, so many 

 landing places in the stairway of organic life. They are, 

 in other words, members of one series since they are alike in 

 many particulars. They differ, however, in the manner of 

 producing their young as well as in other ways. Either the 

 young come from eggs which have been supplied with a large 

 amount of food material and are detached from the mother's 

 body, or they feed for a brief time upon the egg yolk and then 

 attach themselves to the parent's body, drawing their nourish- 

 ment from her through a cord-like tube. Most fishes, frogs, 

 reptiles and birds belong to the first class, and with perhaps 

 two exceptions, all mammals, including man, belong to the 

 second class. In each case the required nourishment is sup- 

 plied to the growing young. Naturally, more protection is 

 afforded the offspring when it is carried within the mother's 

 body, but this is offset by the smaller number of young for 

 which provision can be made. 



In the series which we have chosen to illustrate ascending 

 life, we come now to the bird. Among birds the best form 

 to study is the chick, the little self-sufficient offspring of the 

 humble barnyard fowl. 



The Miracle of Twenty-One Days 



The hen's eggs, even those in process of incubation, are so 

 familiar that we rarely stop to think of what is going on inside 

 the egg in the three short weeks. If one were to take from 

 Biddy, or from an incubator, one egg a day for the first five 

 days and carefully remove the top of the egg, a rapidly chang- 

 ing scene would present itself. 1 One is amazed at the extra- 

 ordinary rate of growth of the chick which is many times 



1 It has been suggested that young children should not be shown the development of 

 the chick, since the opening of the shell involves the death of the embryo, and hence gives 

 the child a shock. The writer has never seen children react in this way, but since the 

 purpose of the demonstration is to show that life exists immediately after fertilization takes 

 place, it should not be continued in later stages if the child is distressed or if it is not con- 

 vinced that the sacrifice is justified by what it teaches. Older children will not offer a prob- 

 lem of this nature. 



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