GROWTH AND HATCHING OF EGGS. hy 
Doctor Smith. Miss Morris and others record a shorter period, and 
there is undoubtedly considerable variation due to weather conditions, 
but the normal period, as shown by the abundant records of this office, 
and many observers, since those noted, ranges, as stated, from six to 
seven weeks. Some interesting instances have been noted of retarded 
development of eggs in plants yielding gummy exudations which had 
hermetically closed the nests from the outer air. Professor Riley 
notes a case of this kind where the eggs remained sound and un- 
hatched until the end of the year, long after the trees had shed their 
foliage. Except in the extreme south, where all of the periods are 
somewhat earlier, the eggs are deposited chiefly in the month of June 
and most abundantly about the middle of this month, and the hatch- 
ing period ranges from the middle of July to the first of August. 
The egg is a very delicate, pearly-white object, about one-twelfth of 
an inch long, tapering to an obtuse point at either end and slightly 
curved. The shell is very thin and transparent, the form of the larval 
insect showing through some time before hatching. As is the case 
with most insects that oviposit in the living parts of plants, the eggs 
of the Cicada receive a certain nourishment from the plant and 
actually increase in size before hatching, 
by absorption of the juices from the a 
adjacent plant cells. ei LETT | | 
Discussing the development of the j,. 4; Se ope icat PO A ab 
embryo, Doctor Potter says that on the enlarged, showing young about to be 
fifteenth day a change in color in the egg “18°? Authors tlustration. 
may be noted, and from this time on there is a gradual increase in 
size, the embryo slowly assuming form—the eye becoming especially 
prominent some ten days before hatching (fig. 45). 
The larval Cicada makes its escape by rupturing the eggshell over 
the back, from the upper end downward about halfway, by muscular 
“movements, accompanied with an inflation of the head and forward 
parts of the body. The rupture in the shell once made, the larva 
works its way out by twistings and contortions until the tip of its 
body only remains in the egg slit of the shell. The entire insect, how- 
_ever, is still inclosed in an extremely delicate and almost invisible 
membrane (amnion), and after resting a short time the violent move- 
ments are again resumed, and by wriggling, twisting, and inflating its 
head, thorax, and anterior parts the thin enveloping skin is burst open, 
and by gradual efforts, coupled with contractions and expansions of the 
body, the larva draws itself out, leaving the thin white skin held in the 
tip of the eggshell. The larve nearest the opening come out first, 
the others following in regular order, each usually pushing out the 
abandoned egesheil of the preceding one, though commonly several 
eggshells remain attached to the loose woody fibers of the egg nest. 
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