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gently over the last quarter of the circle. At last the caterpillar 
finds itself bound on the second side; the head rests on the 
thread-covered plane, and the insect fixes the second end of the 
thread.” , 
It has only to repeat the same manceuvre as many times as 
there are threads wanted to make a strong band. But each 
thread embraces the head, 
how to make each thread 
it spins glide into the 
bend or crease of its 
neck by a little movement of its head. It must disengage this 
head from under the band, not a difficult opera- 
‘tion. It causes it to slide along the threads near ¢ 
one of the places where they are fixed, and it is 
then in the position indicated by the foregoing 
| engraving (Fig. 109). 
| About thirty hours after the caterpillars have 
| succeeded in making themselves fast, they have 
completed their transformation into pup (Fig. 
110). In that the pupa of the above-men- 
tioned caterpillar is seen in two different posi- 
tions, and kept down by the same band which first 
supported the caterpillar. 
Those caterpillars which construct cocoons, make 
them of silk and other substances. These cocoons 
are, for the most part, oval or elliptical, some- 
times boat-shaped, and ordinarily white, yellow, or 
brown in colour. The threads may very slightly 
adhere together, or be closely united by a gummy 
substance with which the caterpillar lines the in- 

Fig. 109.—Caterpillar of the Pieris brassice. 

. PF Fig. 110.—Pupe of 
terior of the cocoon, and which it expels from the _ Pieris brassice. 
anus. Some cocoons are composed of a double envelope, others are 
of an uniform texture. Some are of a tissue so close that they 
entirely hide the chrysalis contained within ; others form a very 
light covering, through which the chrysalis can be easily perceived 
(Fig. 111). 

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