ORGANS OF SECRETION. 583 



muciparous follicles pour out a copious secretion generally 

 near the orifice of the organs of generation, as seen in the 

 earth-worm. Many annelides secrete from the surface of 

 their skin calcareous or other matters to form exterior enve- 

 loping tubes for protection, and many minute marine species, 

 when irritated, give out a brilliant fluctuating light of a 

 bluish -white colour, extending in waves along 'the whole 

 length of their body, and apparently subjected to the will of 

 the animals. The testes and the ovaria, and even the pul- 

 monary cavities, are still in form of simple glandular sacs, as 

 in the earth-worm. 



The liver of the myriapods, as in the scolopendra and the 

 iulus, consists of long isolated biliary tubuli opening into the 

 pyloric end of the elongated gastric cavity, as in insects, and 

 the mouth is furnished with several pairs of long simple 

 salivary follicles. In the scolopendra gigantea, there appear 

 to be three pairs of elongated unequal salivary tubuli extend- 

 ing along the sides of the oesophagus, and opening into the 

 mouth. The chilopoda have two poison-glands placed along 

 the lower maxillee, which convey their acrid secretion into 

 the two unciform palpi placed at the base of the jaws. The 

 genital glands are placed on different sexes, and are fur- 

 nished with several accessory follicles ; the pulmonary sacs or 

 follicles of the annelides, have here become elongated tubuli, or 

 ramified tracheae ; in the chilognatha, small glandular follicles 

 open by minute orifices along the sides, near the haunches of 

 the legs, which secrete an acid and strongly odorous fluid ; 

 and many myriapods emit a bright luminous appearance. 

 Urinary tubuli are already observed in the iulus opening 

 into the lower part of the alimentary canal at the beginning 

 of the dilated colon or rectum, as in many insects. 



The hepatic, salivary, pancreatic, and urinary glands, are 

 distinctly developed in insects, and have generally the form 

 of long isolated tubuli, often provided with small reservoirs, 

 forming a urinary- and a gall-bladder, for the reception and 

 accumulation of their respective secretions before being sent 

 into the digestive canal. The salivary glands form one or 

 more symmetrical pairs of simple tubuli, or clustres of fol- 

 licles, opening by single ducts on each side of the mouth ; 

 and the dilated part of the oesophagus forming the crop, is 

 generally surrounded with numerous minute muciparous 



