106 ZOOLOGY. 



spines, the middle lobe unarmed and spatula-shaped, while the outer 

 forms a five-jointed feeler called the maxillary palpus. The maxillae 

 are accessory jaws, and probably serve to hold and arrange the food 

 to be ground by the true jaws. The floor of the mouth is formed by 

 the labium (Figs. 127 and 128), which in reality is composed of the 

 two second maxillae, grown together in the middle, the two halves 

 being drawn separately in Fig. 127. 



Within the mouth, and situated upon the labium, is the tongue 

 (lingna), which is a large, membranous, partly hollow expansion of 

 the base of the labrum; it resembles a beech-nut in shape, being 

 slightly keeled above, and covered with fine, stiff hairs, which, when 

 magnified, are seen to be long, rough, chitinous spines, with one or 

 two slight points or tubercles on the side. 



The internal anatomy may be studied by removing the dorsal wall 

 of the body with fine scissors, and also by hardening the insect sev- 

 eral days in alcohol and cutting it in two longitudinally by a sharp 

 scalpel. 



The ozsopliagus (Fig. 130, a) is short and curved, continuous with 

 the roof of the mouth. The two salivary glands consist each of a 

 bunch of follicles, emptying by a common duct into the floor of the 

 mouth. 



The oesophagus is succeeded by the crop {ingluvies). It is in the 

 crop that the "molasses" thrown out by the locust originates. 



The proventriculus is very small in the locust, easily overlooked in 

 dissection, while in the green grasshoppers it is rather large, and 

 armed with sharp teeth. The true or chyle-stomach is about one 

 half as thick as the crop. 



From the anterior end arise six large pockets {gastric cevca), which. 

 arise from the true chyle-stomach, and probably serve to present a 

 larger surface from which the chyle may escape into the body-cavity 

 and mix with the blood, there being in insects no lacteal vessels or 

 lymphatic sj'stem. 



The stomach ends in a slight constriction, at which point the 

 urinary tubes (Fig. 130, ur) arise. These are arranged in ten groups 

 of about fifteen tubes, so that there are about one hundred and fifty 

 long, fine tubes in all. The stomach is succeeded by the ileum, 

 colon, and rectum (Figs. 130, 131). 



The nervous system of the locust, as of other insects, consists of 

 a series of swellings or nerve centres, or so-called brains (ganglia), 

 which are connected by two cords (commissures), the two cords in 

 certain parts of the body in some insects united into one. There are 

 in the locust ten ganglia, two in the head, three in the thorax, and 

 five in the abdomen. The first ganglion is rather larger than the 

 others, and is called the " brain." The brain rests upon the cesoph- 



