NO. 2 RECOGNITION AMONG INSECTS McINDOO 59 



De Rougemont (1879) describes the organ causing the explosions 

 in Brachinus crepitans as a paired structure in which the collecting 

 tube is a double canal. Its inner tube which is filled with air is 

 arranged spirally inside the cylindrical outer tube. The anterior 

 end of this double tube is divided into two branches which are also 

 filled with air and the walls of these branches are composed of gland 

 cells. A brown liquid, butyric acid, is found in the reservoir. The 

 author thinks that this acid is passive as long as it remains in the 

 reservoir, but when it is discharged to the outside by the force of 

 the condensed gas inside the collecting tube, it becomes active and 

 produces a strong odor. 



Bertkau (1882b) describes the anal gland of both sexes of the 

 click beetle, Tacon muriniis, as a saclike cavity which is protruded 

 when its secretion is discharged; the sac is retracted by a muscle. 

 The spherical gland cells lie in the walls of this large sac. The 

 long, fine, and entwined secreting tubules arise beside the nuclei of 

 the gland cells and several of them run into the sac at the same point. 

 Each tubule begins as a faint swelling in the cytoplasm of the uni- 

 cellular gland, but he noticed no vesicle. The lower portion of the 

 sac serves as a reservoir where the secretion is collected. 



Williston (1884) reports that when either sex of Eleodes longi- 

 collis is disturbed, it discharges a pungent and vile smelling fluid 

 from the anal glands. 



Townsend (1886) placed some carabids, Calathus gregarius, in 

 a bottle, and subsequently the bottle was filled with white smoke, 

 which he concludes was brought about by the anal glands. 



Loman (1887) discovered that a beetle, Cerapferus maculatus, 

 from Java causes loud explosions when the secretion of its anal glands 

 is discharged. He found that this secretion, which is to guard off 

 enemies, contains free iodine. 



Gilson (i889a-b) describes the anal glands of Blaps mortisaga 

 as two cylinders which unite to form a short tube. This tube opens 

 at the lower part of the last intersegmental space of the abdomen. 

 Each cylinder is a sac whose walls are covered with a large number of 

 whitish lobes. While the sac is a reservoir, each lobe is a collec- 

 tion of unicellular glands. He says that these cells constitute the 

 most complete type of unicellular glands and one of the most com- 

 plicated forms of all cells. Besides having a conspicuous nucleus, 

 each gland cell has a radiating vesicle, a central ampulla, a secreting 

 tubule and a sheath around the tubule. The cytoplasm of the cell 

 contains radial streaks which radiate toward the vesicle. The club- 



