MICROSCOPIC DRAWING AND ENGRAVING. 



generally straight, curves itself in the shape of the letter S when 

 the creature seizes its prey. During the summer the larva is said 

 to attain its full size jn about fifteen days, when it quits the 

 water and creeps into the neighbouring earth, where it forms with 

 considerable skill a round cell, in which, in about five days, it 

 changes to a pupa of a whitish colour, with two obtuse points at 

 the extremity of the body. In about a fortnight or three weeks it 

 issues as a perfect beetle. If, however, the change to the pupa 

 state take place in the autumn, the creature does not pass into the 

 form of a perfect insect until the following spring. 



The beetle is at first soft and yellowish, but soon hardens and 

 assumes a darker colour. It is not, however, until the end of 

 eight days, that it has acquired its proper consistency.* 



Dr. Goring, in describing the specimen from which the drawing 

 was taken, says that the three first segments of the body, com- 

 mencing from the neck, contain a bundle of nerves, terminating 

 with three loops, which are very perceptible in the young larva, 

 being of a colour more brilliant than the other parts of the body. 

 They are shown in the figure like a bundle of strings or cords, 

 extending from the centre of the head to the extremity of the 

 third joint of the body. 



The two large trachea?, commencing from the head, attain 

 their greatest development about the third joint of the body. 

 They follow the sides of the body to a point near its extremity, 

 where they coalesce and terminate. These air-tubes, in their 

 passage along the body, throw out numerous ramifications, which 

 are shown in the figure. These tracheae are four in number, two 

 interior and two exterior. The interior ones commence at the 

 ganglion, which terminates at the third joint of the body, and 

 they disappear at the third joint from the tail. In the last joint 

 Trat one is situated the organ of pulsation. 



58. Dr. Goring has also left two very beautiful engravings of 

 the larva and the pupa of the gnat, taken from a specimen of the 

 species called tipula crystallina of De Geer, the chironomus 

 plumicornis of Fabricius, and the corethra plumicornis of 

 Stephens. I have reproduced these beautiful objects from Dr. 

 Ooring's engravings, the larva being represented in fig. 1, the 

 pupa in fig. 2, and a plan, or bird's-eye view of the larva, in its 

 natural size, in fig. 3. 



The gnat, of which these are the previous forms, is represented 

 in fig. 36, the drawing having been taken while the creature was 

 in the act of laying the cluster of eggs figured on the right side. 

 The short line between the figures gives the real length of the 



* Westwood on "Insects," vol, i., p. 95. 

 90 



