BILE 79 



controversy. The coiu'se they take may be studied by killing animals 

 at varying periods after a meal of fat, and making osmic acid micro- 

 scopic preparations of the \411i. Figs. 26 and 27 illustrate the 

 appearances observed by Professor Schafer. 



The columnar epithelium cells become first filled with fatty globules 

 of varjnng size, which are generally larger near the free border. The 

 globules pass down the cells, the larger ones breaking up into 

 smaller ones during the joiirney ; they are then transferred to the 

 amoeboid cells of the IjTnphoid tissue beneath : these ultimately 

 penetrate into the central lacteal, where they either disintegrate or 

 discharge their cargo into the lymph stream. The globules are 

 by this time divided into immeasurably small ones, the molecular 

 basis of chyle. The chyle enters the blood stream by the thoracic 

 duct, and after an abundant fatty meal the blood plasma is quite 

 milky ; the fat droplets are so small that they circulate without 

 hindrance through the capillaries. The fat in the blood after a 

 meal is eventually stored up in connective tissue cells of adipose 

 tissue. It must, however, be borne in mind that the fat of the body 

 is not exclusively derived from the fat of the food, but it may 

 originate also both from proteid and from carbohydrate. 



As, however, the fat globules were never seen penetrating the 

 striated border of the epithelial cells, there was a great difficulty in 

 anderstanding how they reached the interior of these cells ; the cells 

 will not take up other particles, and it appears certain that they do 

 not in the higher animals protrude pseudopodia from their borders 

 (this, however, does occur in the endoderm of some of the lower 

 invertebrates). 



Eecent research has in a great measure solved this difficulty. In 

 the first place particles may be present in the epithelium and lym- 

 phoid cells while no fat is being absorbed. These particles are pro- 

 toplasmic in nature, as they stain with reagents that stain proto- 

 plasmic granules ; they however also stain darkly with osmic acid, 

 and so are apt to be mistaken for fat. There is, however, no doubt 

 that the particles found during fat absorption are composed of fat. 

 There is also no doubt that the epithelial cells have the power of 

 again forming fat out of the fatty acids and glycerin into which it has 

 been broken up in the intestine. Munk, who has performed a large 

 number of experiments on the subject, showed that the splitting of 

 fats into glycerin and fatty acids occurs to a much greater extent 

 than was formerly supposed ; these substances being soluble pass 

 readily into the epithelium cells ; and these cells perform the syn- 

 thetic act of building them into fat once more ; the fat so formed 



