44 Mr Hardy and Mr Mc Dougall, On the Structure [Jan. 30, 



The second movement consists of a quick contraction of the 

 walls of the liver diverticula which occurs at irregular intervals 

 during the progress of digestion and which is apparently due to 

 the stimulation of the walls of the liver diverticula by innutritions 

 food particles. It is difficult to be certain on this point, but so 

 far as our observations go they agree with this view of the 

 causation of the movement. 



It is clear that the first movement is the agent which propels 

 the soluble products of digestion and the freed discrete food 

 particles to the anterior region of the mesenteron. The con- 

 tractions of the liver diverticula on the other hand serve to drive 

 the innutritious residue of these particles back to the middle 

 and posterior regions. 



The effect of these two movements may be made clear by 

 taking the case of an animal fed on a mixture of yolk of egg^ 

 and carmine. The yolk particles, consisting mainly of proteid 

 precipitate aiid fat globules, and the carmine grains form at first 

 an agglutinated mass in the middle region of the gvit. As so- 

 lution proceeds the fat globules and carmine grains are liberated 

 and are driven in relatively small numbers into the anterior 

 region, where the former are taken up by the lining epithelium 

 so that the walls become in time thickly studded with fat drops. 

 The carmine particles are not taken up but are at intervals driven 

 back by contractions of the liver diverticula to the middle 

 region. 



Absorption, By feeding with food rich in fat globules we 

 can determine the region in which the absorption of solid par- 

 ticles occurs, and we find that fat is most readily taken up 

 by the cells of the anterior region, including the liver diver- 

 ticula. If the amount of fat given be not great, globules appear 

 practically only in this region. If however a large quantity is 

 ingested, in 24 to 40 hours the cells of the middle region also 

 become considerably loaded but always to a much less extent 

 than those of the anterior region. The globules of fat in the cells 

 differ in size in the two regions, thus in one animal the globules 

 in the cells of the liver diverticula measured 3 to 5 yu, in diameter, 

 in the anterior region of the mesenteron they measured 4 to 7 //. ; 

 while in the middle region the globules were relatively scanty 

 and too small to measure. 



If the fatty diet be pushed to great excess fine globules may 

 occur in the cells three quarters of the way back along the 

 mesenteron. 



It is however quite clear that the absorption of fat is practi- 

 cally confined to the anterior third of the mesenteron. 



Our reasons for supposing that absorption of the dissolved 

 products of digestion is especially the function of the anterior 



