MECHANORECEPTION 45 



Orthoptera, Hymenoptera, and Lepidoptera by Slifer and Finlayson 

 (1956) and Finlayson and Lowenstein (1955, 1958). 



Three types of stretch receptors are known : those associated with 

 connective tissue, those associated with muscle, and those consisting 

 of a specialized muscle fibre. They are represented by receptors in 

 dragonfly larvae, bees, and cockroaches, by those in Orthoptera, and 

 by those in moths respectively. 



Each connective tissue receptor is a multipolar neuron embedded in 

 a strand of connective tissue which stretches either from an inter- 



FiG. 35. Right half of the sixth abdominal segment of a full-grown larva of 

 Aeschna juncea with various muscles cut to reveal the three stretch 

 receptors. Dva, dorso-ventral anterior muscle; Dvm, dorso-ventral 

 median muscle; Dvp, dorso-ventral posterior muscle; Sx, sextic 

 longitudinal tergal muscle; Obi, oblique receptor; Lo, longitudinal 

 receptor; Ve, vertical receptor. (Redrawn from Finlayson and 

 Lowenstein, 1958.) 



segmental fold or from a nerve to a point on the body wall (Fig. 34). 

 In the cockroach Periplaneta americana a pair has been found in the 

 dorsal region of abdominal segments two to seven. In dragonfly larvae 

 {Aeschna juncea) three pairs of receptors have been found in each 

 abdominal segment one to eight (Fig. 35). In the honeybee there is a 

 pleural pair in each abdominal segment three to six. In all cases the 

 neuron is encapsulated in connective tissue. The capsule is multi- 

 nucleated. Detailed studies with light- and electron microscopy of 

 the abdominal stretch receptor of the cockroach Blaberus (Osborne 

 and Finlayson, 1962; Osborne, 1963) have shown that the terminal 



