ON EMBRYONIC DIFFERENTIATION 275 



of things," for instance, when a mere local increase of 

 "flatus" obtains, the positions usually assumed, or 

 affected, agree with the positions of the principal sphinc- 

 ters of the intestinal canal, viz. the cardiac, and pyloric, 

 the ileo-cascal, the sigmoid flexure, and anal sphincter. 



When morbid obstructive bowel phenomena have to be 

 practically dealt with, it becomes absolutely necessary to 

 bear these elementary facts in memory. 



The adaptation, therefore, of the anterior limb of the 

 V-shaped neurenteric canal, to the requirements of an 

 apparatus, for the preparation of alimentary materials for 

 nutritional purposes, may be regarded as transcendently 

 complete, and absolutely adapted, to meet its every 

 requirement, from whatever aspect its details, individual, 

 and communal, can be viewed. It need scarcely be added 

 that the posterior limb of the neurenteric V is the only 

 other evolutional product, in its finished state, in any way 

 comparable, in its details, and adaptation, to functional 

 purposes, which can be met with in the whole course, and 

 history, of evolution, organic, or inorganic. .We cannot, 

 therefore, but regard these two neurenteric evolutionary 

 products as the "crown, and head" of the anatomical 

 sequence, reaching from the amceba to the last vertebrate, 

 and from the first to the last of that great biological 

 ascent, or descent, known to natural science and revela- 

 tion alike, as " life on earth." In this connection, it 

 only remains to add that these two divisions of the 

 neurenteric canal, in their fully evolved condition, of 

 structural, and functional, fitness, are fitly joined together, 

 and operated, by the great dynamic organism, the heart, 

 and blood vasculature, with the result, that the greatest 

 biological wonder in our world, thus, becomes accom- 

 plished, and visible, in the form of man, with all his 

 attributes, and aspirations, his physical, and mental, 

 faculties, his powers to realise the past, and the present, 

 and his ability, to some extent, to grasp, and anticipate, 

 the future, as well as to evolve, and apply, the principles 

 of justice, ethics, and morals, in relationship to himself, as 

 well as to his fellow-men. 



Digestion, thus, is a very long, and complicated, process, 

 combining, as it does, the use of mechanical, chemical, 



