398 Animal Biology 



is composed of a long visual rod, and the various ommatidia are separated 

 from each other by a layer of dark pigment cells. Such an arrangement 

 gives mosaic vision in which each ommatidium receives a portion of the 

 image. 



Each simple eye or ocellus consists of a group of cells, the retinulae (L. 

 rete, net) ; a central optic rod, the rhahdom (Gr. rhahdos, rod) ; and a 

 transparent, cuticular "lens." The ocelli probably function as light-per- 

 ception organs. 



The pair of jointed, threadlike antennae (an -ten' i) (Gr. ana, up; 

 teino, stretch) bear sensory bristles probably for olfactory (ol -fak' to ri) 

 (L. olere, to smell; facere, to make) purposes. Organs of taste (gusta- 

 tory) are located on the mouth parts. Hairlike organs of touch (tactile) 

 are present on various body parts but particularly on the antennae. The 

 pair of sound-receiving auditory organs located on the sides of the first 

 abdominal segment consists of a membranous tympanum (tim' pa num) 

 (Gr. tympanon, drum) which covers an auditory sac. 



Reproduction. — The sexes are in separate grasshoppers (diecious). 

 The female possesses a conspicuous ovipositor (o vi -poz' i tor) (L. ovum, 

 egg; ponere, to place) at the tip of the abdomen for depositing eggs. In 

 the female, one pair of ovaries produce eggs which are discharged into a 

 pair of oviducts. The latter unite to form a vagina connected with the 

 genital pore between the parts of the ovipositor. A seminal receptacle 

 (spermatheca) connected with the vagina receives sperm from the male 

 during copulation and releases them to fertilize eggs. A secretion of the 

 cement gland may stick eggs together as they are deposited. 



In the male, one pair of testes discharge sperm into a pair of vasa 

 defer entia (sperm ducts) which unite to form the ejaculatory duct that 

 opens at the posterior end of the abdomen. Accessory glands secrete a 

 fluid into the ejaculatory duct to aid in the transfer of sperm to the 

 female. Eggs are fertilized by sperm when they are deposited. A young 

 grasshopper which hatches from an egg is called a nymph (nimf) (Gr. 

 nymphe, immature stage) and resembles an adult without wings. As 

 the grasshopper grows, it must shed its chitinous exoskeleton at certain 

 intervals by the process of ecdysis (moulting). Adult wings are event- 

 ually formed from wing buds. 



HONEYBEE (Figs. 195 to 200) 



The honeybee, Apis mellifica (L. apis, bee) (me-lif'ika) (L. mel- 

 lificus, honey), belongs to the order Hymenoptera (hi men -op' ter a) 

 (Gr. hymen, membrane; ptera, wings) because of its two pairs of mem- 



