THE LIVER. 159 



this substance into dextrose as occasion requires. It also stores fats, 

 reserving- them for the needs of the organism. It elaborates the 

 bile-salts and pigment, deriving material for the latter from the 

 haemoglobin of the blood. In addition to these functions, many 

 synthetical processes occur in the liver. The nitrogenous waste- 

 products of metabolism in other parts of the body are here changed 

 into forms suitable for excretion by the kidney. Most of the urea 

 appearing in the urine is formed in the liver. Injurious substances 

 absorbed from the intestine are, at least in many instances, combined 

 in the liver with chemical radicals to form less toxic compounds 

 which can be eliminated. It therefore exerts an important detoxi- 

 cating influence highly beneficial to the other organs and cells of the 

 body. In view of these numerous functions and the great versatility 

 displayed by the liver-cells, it is not surprising to find that by 

 special methods of preparation very diverse structural appearances 

 are presented by these cells, and that these appearances vary with 

 the condition of the liver at the time of its removal from the 

 body. Some observers believe that the intercellular bile-radicles 

 described by others are artefacts, and not permanent structures. 

 Some investigators have ascribed amoeboid movements of limited 

 range to these cells, and have noted the presence of red blood- 

 corpuscles within the cytoplasm, apparently incorporated by active 

 movements of the cell-body. Injections have even been made to 

 penetrate the nucleus. Diversities in apparent structure, of which 

 these are merely a few examples, render it impossible to give a brief 

 adequate description of the typical liver-cell or to connect definitely 

 the observed structures with any particular function. 



It will, perhaps, make the structure of the liver a little more 

 comprehensible if it is stated that the liver of some of the lower 

 animals is a tubular gland, the tubes of which are lined with a layer 

 of epithelium. In the human liver this tubular structure is dis- 

 guised by the facts that the tubules anastomose with each other, and 

 that their lumina are very minute and bounded by only two cells 

 when seen in cross-section. So inconspicuous are these lumina that 

 a casual glance at a section of a liver would not reveal the fact that 

 it was a glandular organ. 



The interstitial tissue of the liver consists of a few sparsely 

 distributed fibres continuous with those of Glisson's capsule. 



The intricate structure of the liver prepares us for the fact that 

 its function is an extremely complex one. It is a secreting gland, 



