4i 6 
TRANSFORMATIONS OF INSECTS. 
wiggling and much trouble to get out of the old skin. When 
the skin has been got rid of, the singular fact comes to light 
that another large segment and two more pairs of legs are added, 
so that the Pciuropus becomes a ten-legged animal. After a 
while the insect moults again, and at each change of skin obtains 
a fresh pair of legs, and at last nine pairs are developed. 
The three pairs of primitive legs so characteristic of the true 
insects are speedily added to during the growth of the young 
Jitlus, and that this is the case will be gleaned from Newport’s 
description of the Myriapod from its earliest observable state. 
The development of the young Jidns is divided by Newport* 
into several distinct and well-marked periods. The first period 
extends from the deposition of the egg to the gradual bursting 
of the shell and the exposure of the embryo within, occupying 
the space of twenty-five entire days, during which the egg acquires 
a sensible increase of bulk. 
On the nineteenth day there was a complete alteration in the 
form of the egg. It was more obtuse at both ends, and had 
become much larger, and the outline of the embryo, coiled up 
within the shell and nearly filling the whole interior, was very 
distinct, although as yet there were no rudiments of limbs or 
even of a division of the body into distinct segments. On the 
following day (the twentieth) the outline of the embryo was 
more apparent, and on its concave or ventral surface there were 
faint traces of a division of the body into six segments. Up 
to this time Newport was unable to detect an umbilical cord 
attached to the embryo. From this time the egg became larger 
every day, until the twenty-fifth day, when it was greatly distended, 
and began to assume a kidney-shaped appearance, and commenced 
bursting along the back, the back of the white embryo gradually 
passing through the opening (Fig. i). 
In the second period of development the embryo is exposed 
to a new medium, and perhaps derives the means of its further 
growth from external sources, although it is still enveloped in 
the foetal membranes, and retains its connection with the shell. 
# Quoted from Rymer Jones’ article “Myriapoda,” in the “ Cyclopaedia of Anatomy 
and Physiology.” 
