588 ORGANS OF SECRETION. 



pyloric extremity of the capacious masticating stomach. They 

 are connected together by their points of junction, by their 

 common peritoneal covering, by a loose interposed cellular 

 tissue, and by the minute ramifications of the hepatic arteries 

 which afford the materials of their secretion. The branches 

 of the two primary ducts determine the lobes, and their 

 branches, the minuter lobules, and the terminal tubuli are 

 commonly filled with their yellowish-brown coloured secre- 

 tion. By removing a portion of the peritoneal investment, 

 and agitating a small piece of the liver gently in water, the 

 component tubuli, which are disposed with their shut ends 

 around the periphery of the lobes, are easily separated from 

 each other, and rendered obvious to the naked eye. 



The soft green-coloured pulpy substance on each side of 

 the oesophagus, composing the salivary glands in many of 

 the decapods, more resembles a vascular blastema than rami- 

 fied tubuli; and the pancreas of these highest Crustacea, 

 consists only of two or three elongated, simple, isolated 

 tubuli, opening into the digestive canal, beyond the entrance 

 of the hepatic ducts. The generative glands, the ovaria and 

 tesles, present a greater subdivision of their terminal, secre- 

 ting, coecal portion, and a greater distinction of this part 

 from the efferent ducts, than in most of the inferior articulata. 

 From the simple tubular structure thus presented by the 

 various glands of the articulated classes, they not only ex- 

 hibit permanent types of the primary transient stages of 

 these organs in higher animals, but afford most instructive 

 analyses of all the most complex conglomerate forms of 

 secreting organs met with in the animal kingdom, and in the 

 regularity of their forms and their bilateral symmetry, they 

 surpass the glands of all other tribes of animals. 



FOURTH SECTION. 



Secreting Organs of the Cyclogangliated or Molluscous 



Classes. 



The high development of the sanguiferous system in the 

 molluscous classes, their mixed and inferior kind of food, 

 and their imperfect means of locomotion, prehension, and 



