392 Introduction to Animal Morphology. 



dilatations. In many Hymenoptera they are nume- 

 rous and short; in some Orthoptera over 100, and in 

 Gryllotalpa, where they are numerous, they unite into 

 a single duct. In Melolontha they open into a 

 small caecum : they contain uric acid, oxalic acid and 

 leucin. 



There is no liver: in some Hemiptera and Orthop- 

 tera caecal tubes are described as pancreatic. The 

 fatty body is large in larvae, yellow, lobed, often fas- 

 tened to the body wall and to the viscera which it 

 suspends; around it are often netted tracheal branches. 

 Its materials are used up in the pupa stages, and it di- 

 minishes as the sex-organs mature. In Lampyris it 

 is modified into the luminous organ, which consi^ 

 a flat transparent lamella of polyhedric cells, richly 

 supplirdwith tracheae and nerves. On the dorsal side 

 t on a layer of white opaque non-luminous 

 cells, which contain concretions of urea. Probably the 

 luminous organ in Elater is similar. 



The blood is colorless, green, or red, with clear 

 nucleated corpuscles and fat granules. The heart is 

 1, tubular, chambered, as in Myriapods, but 

 lying in the abdomen, supported by triangular liga- 

 moita alaria, or Htiisculi, one attached to the outer 

 connective coat of each chamber, and slung thereby to 

 the body wall, and often to the neighbouring tracheae ; 

 it is continued forwards, as the cephalic aorta, into 

 the thorax and head. There are usually eight cham- 

 bers, each of which receives blood through a pair of 

 venous ostia guarded by valves, and sends its blood 

 into the one before it, regurgitation being prevented 

 by valves, until it reaches the aorta, from whence the 

 blood returns by lacunae to the heart. There is no 



