TRANSFORM ATIOXS OF THE INSECT. Gl 



On review it will be seen how remarkable are the changes in 

 form of the insect before it is hatched, and that all are the 

 resnlt of simple growth. We have seen that the two ends of 

 the body are first formed, and that the under side of the body 

 is formed before the back ; that the bell}'^ is at first turned out- 

 wards, and afterwards the embryo re^'erses its position, the 

 back presenting outwards. All the appendages are at first 

 simple protrusions from the body-walls, and new segments are 

 interpolated near the tip of the abdomen. These changes take 

 place very rapidly, within a very few days, and some of the 

 most important and earlier ones in a few hours. We can now 

 better understand that the larva and pupa stages are the result 

 of a similar mode of growth, though very marked from being 

 in a different medium, the insect having to seek food and act 

 as an independent being. 



Transformations of the Insect. We have seen that 

 during the growth of the embryo, the insect undergoes remark- 

 able changes of form, the result of simple growth. The meta- 

 morphoses of the animal within the egg are no less marked 

 than those which occur after it has hatched. It will also be 

 seen that the larva and pupa stages are not always fixed, defi- 

 nite states, but only pauses in the development of the insect, 

 concealing beneath the larva and pupa skins the most impor- 

 tant changes of form. 



The process of hutdiiucj. No other author has so carefully 

 described the process of hatching as Newport, who observed 

 it in the larva of Melos. "When the embryo larva is ready 

 for its change, the egg-shell becomes thinned and concave on 

 that side which covers the ventral surface of the body, but is 

 nuich enlarged, and is more convex on the dorsal, especially 

 towards the head. The shell is then Inu-st longitudinally along 

 the middle of the thoracic segments, and the fissure is ex- 

 tended forwards to the head, which then, together with the 

 thoracic segments, is partially forced through the opening, but 

 is not at once entirely withdi'awn. The antennas parts of the 

 mouth, and legs are still inclosed within separate envelopes, 

 and retain the larva in this covering in the shell. Efforts are 

 then made to detach the posterior segments of the body, which 



