280 BIOLOGICAL PHYSICS 



expulsion, by the principle, as before stated, of a " faeci- 

 meter," or alvine regulator. 



The alimentary or intestinal canal in both instances is 

 held in position by a series of anatomical structures 

 variously disposed and adapted to maintain its horizontality 

 or perpendicularity as the case may be, while providing for 

 its divisional and general patency, and securing, in stages, 

 the performance of its functional work, by the provision, in 

 its lumen, of a series of "shut" or valved "sacs," in 

 which the particular acts of digestion are carried out seriatim 

 and the process of nutrition ministered to. 



These supporting structures and divisional dispositions 

 of the canal are known to anatomists by various names, 

 and when seen in whole, and regarded from the point of 

 view of design, and as effective adaptation of means to 

 ends, inspire the observant student as he, however slightly, 

 realises their import, with a feeling akin to that of the 

 astronomer when he succeeds in unravelling the details of 

 a solar system, or the terrestrial explorer when he discovers 

 a " dark continent." 



Beyond this faecimeter, or alvine regulator, is the last, or 

 concluding, compartment of the intestinal canal, known as 

 the rectum (see Figs. 1 13, 1 15) from its straight disposition, 

 a pouch, or alvine chamber, in which, as in a cloaca, the 

 residual alimentary materials quickly or slowly accumulate 

 for periodical discharge under, more or less, the voluntary 

 control of the individual, through or by the aid of the 

 systematically innervated anal sphincter, and associated 

 abdominal expulsatory musculature. 



Conducing to the functional facility of intestinal evacua- 

 tion is the moistening, or lubrication, of the intra- and 

 extra-anal, and proper rectal structures, effected by the 

 posterior outfall agency of the cerebro-spinal fluid, where 

 it empties itself from the coccygeal gland apparatus (see 

 Fig. 113), in the manner elsewhere described, and where 

 it seems to us to maintain the structural and functional 

 continuity of the once undivided embryonic neurenteric 

 canal, and to demonstrate the subsequent oneness of the 

 great circulatory economy existent amid the permanent 

 and final structural dispositions and visceral differentiations 

 of the adult body, as they have directly descended from, 



