THE PERIODICAL CICADA 



The procedure of the female in placing the eggs leaves 

 no doubt that the first-laid ones are those at the bottom of 

 the cell, showing that the order of laying has no relation to 

 the order of hatching, except that it is mostly the reverse. 

 It seems hardly reasonable to suppose that the eggs nearest 

 the door are affected by greater heat or by a fresher sup- 

 ply of air, so it is suggested that the order of hatching 

 may be due simply to the successive release of pressure 

 along the tightly packed rows, giving the compressed 

 embryos a chance to squirm and kick enough to split the 

 inclosing shells. When hatching once commences it pro- 

 ceeds very rapidly through the whole nest, showing that 

 the eggs are all at the bursting point when the rupture of 

 the first takes place. 



In each lateral compartment of an egg nest the eggs 

 (Plate 8, E, F) stand in two rows with their lower or 

 head ends slanted toward the door. (It must be re- 

 membered that the punctures are made on the lower sides 

 of the twigs, so that the eggs are inverted in their natural 

 position in the nests.) On hatching, each egg splits ver- 

 tically over the head and about one-third of the length 

 along the back, but tor only a short distance on the 

 ventral side. As soon as this rupture occurs, the head 

 of the young cicada bulges out; and then, by a bending 

 of the body back and forth, the creature slowly works its 

 way out of the shell, which, when empty, remains behind 

 in its original place. The nymphs nearest the door have 

 an easy exit, but those from the depths of the cell find 

 themselves still in a confined space between the project- 

 ing ends of the empty shells ahead of them and the chamber 

 wall, a passage almost as narrow as the egg itself, through 

 which the delicate creatures must squirm to freedom. 



A newly-hatched or a newly-born aphid, as we have 

 seen in Chapter VI, is done up in a tight-fitting garment 

 with neither sleeves nor legs, but nature has been more 

 considerate in the case of the young cicada. It, too, 

 comes out of the egg clothed in a skin-tight jacket, but 



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