316 



ANIMAL BIOLOGY. 



[Part 1 1. 



into the renal gland, may be seen to emerge by an irregular 

 opening. The vestibules communicate by an inter-renal aper- 

 ture. Anteriorly there is a small aperture in the floor of each 

 vestibule. Through it may be passed a guarded bristle, which 



o.g. 



ves. 

 FIG. 92. MUSSEL : HEART AND RENAL ORGAN. 



a. ad. Anterior adductor muscle, a. r. m. Anterior retractor muscle. 

 au. Auricle, e. re. a. External renal aperture, g. a. Generative aperture. 

 i. g. Inner gill. i. r. a. Aperture between glandular portion and vestibule, 

 fc. o. Organ of Keber. o. g. Outer gill. p. ad. Posterior adductor muscle. 

 p. c. Pericardial chamber, p. p. Protractor pedis muscle, p. r. m. Posterior 

 retractor muscle, r. Rectum, re. Glandular part of renal organ, re. p. a. 

 Reno-pericardial aperture, ve. Ventricle, ves. Vestibule of renal organ. 



will emerge by the external renal aperture close to the anterior 

 end of the inner gill. (The dotted arrow in Fig. 92 passes 

 through this aperture.) The cavity of the glandular part may 

 now be opened up, its brownish solid contents washed out, and 

 the irregular walls noted. 



In a second mussel the renal organ may be dissected from 

 the side, and the parts laid open and carefully drawn with the 

 guidance of the diagram, Fig. 92. 



The secretion of the renal organ has recently been shown to 

 contain uric acid and urea. These substances were also found 

 in the blood of the central blood sinus, but none was found in 

 blood taken from the gills. 



