MICROSCOPIC OBJECTS. 64 



Fig. 127. Gizzard of House-Cricket (Acheta domestica), 



x20. 



The variety of gizzards and gastric teeth to be found in 

 insects, more especially in the orders Orthoptera and Coleo- 

 ptera, is to a certain extent unlimited ; a field is open here 

 for wide research, especially in foreign insects. The beauty 

 of these structures will always make them attractive objects 

 to microscopists. The dissection of a gizzard taken from the 

 House-Cricket will lead the way for further inquiry and re- 

 search. 



The mode of preparation is to separate the gizzard from 

 the alimentary canal, cut it open with a fine pair of scissors, 

 boil it in a weak solution of potassa fusa until clean, wash in 

 warm water, and mount in a cell containing acetic acid. 



Fig. 128. Noise-apparatus of House- Cricket (Acheta 

 domestica) , x 20. 



The well-known song of the Cricket perhaps requires a 

 slight explanation. The upper coriaceous wings of this insect 

 possess near their inner margin a short, horny, and rasp-like 

 apparatus, one to each wing. By the rapid motion given to 

 the wings by the strong voluntary muscles, on the rasp- like 

 bodies touching each other they produce a sound not unlike 

 the chirping of some young birds ; the sound is also greatly 

 assisted by the membranous substance stretched over the 

 surface of the wings. The drawing represents the rasp-like 

 bodies in the act of producing the sound. The wings must 

 be well washed, dried under pressure, soaked in turpentine, 

 and mounted in balsam. 



