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TRANSFORMA TIONS OF INSECTS. 
In 1824 Heroldt described the changes which occur in the 
eggs of the spider (pulmoniferous) before it was hatched, and 
his investigations are a wonderful piece of intelligent and patient 
research. He divides the growth of the spider within the egg — 
from its first appearance as a shapeless and structureless germ 
to the perfect condition when hatching took place — into eleven 
stages, but there is not a strict line of division between the stages, 
only different organs are formed, and various appearances are 
presented gradually. 
Up to the period which Heroldt terms the seventh, the body 
of the spider looks like an opaque structureless mass, but when 
this commences, traces of rings, four in number on either side, 
may be noticed. These are the rudiments of the legs. They 
occupy the side of the front part of the egg, and they are extended 
downwards also. The end of the first leg is close to that of the 
opposite side ; but the three others, though of greater length, 
are separated by a space which is filled with a cloudy and some- 
what transparent matter. This space is subsequently occupied 
by the trunk and much of the abdomen. The future head is in front, 
but is not yet rounded like in the perfect spider, but is flattened 
forwards, and there is a ring on its sides which forms the palpi 
of the jaws, and portions of the mandibles may be distinguished 
in a very rudimentary condition. It is probable that all the parts 
which appertain to the head, as the eyes, the hooks or the 
mandibles, and the maxillae or jaws, have their limits well defined 
at this period. In the preceding period, or the sixth, only the 
general outlines of the head and body could be distinguished. 
With respect to the head, it is nearly separated from the chest 
(as in insects), and this fact is of importance, since in all the 
full-grown spiders the confluence of the head and chest is most 
intimate, and their original separation only indicated by a groove 
of greater or less depth. 
The integument or skin of the foetal spider begins to be seen 
at this time, and can be detected in the form of furrows or arched 
folds. 
During the eighth period the feet, mandibles, and the head 
become more definite as structures, and the whole ovum 
diminishes in size in front, and is somewhat constricted so as to 
