MECHANORECEPTION 35 



Tactile receptors are usually of the velocity-sensitive type and are 

 most common on those portions of the body that encounter the en- 

 vironment as the animal progresses or on those appendages with which 

 the animal explores its environment. Pressure-sensitive receptors are 



.hf^H^^^*^^llk0iifm0^F^'^i ( I i ! 1 1 I 1 I 



M 



4.0 

 MV 



I 



i4iYiTfrrf^T>^^ 



Fig. 25. Response of a mechanosensory hair on the second antennal joint 

 of Melanoplus to increasing mechanical stimulation. Approximate 

 onset of stimulation is indicated by arrow. The stimulus continues until 

 the end of the record. A and B are responses to successive stimuli of 

 approximately the same size. Positive at the recording electrode is 

 down. Time marks recur at 0-2-second intervals. (Courtesy of M. L. 

 Wolbarsht.) 



most common on those areas where positioning is important. They are 

 found, for example, in the genital regions and between joints. They 

 are proprioceptors. 



PROPRIOCEPTORS 



Proprioceptors may be defined as sense organs capable of continuous 

 response to deformations (changes in length) and stresses (tensions 

 and compressions) in the body (Lissmann, 1950). They provide some 

 of the information necessary for the animal to maintain certain re- 

 lations of one part of the body with another and of the body as a whole 

 with respect to gravity. In this capacity they are assisted by other recep- 

 tors, as photo- and tactile receptors, for example, whose primary 

 function may lie in another realm. In other words, the insect maintains 

 position by assessing much information from a multitude of receptors. 



