332 GENERAL PHYSIOLOGY 



diseases, such as tuberculosis, heart-diseases, kidnej'-diseases, etc., 

 in the kidney, heari, liver, blood-vessels, etc. (Fig. 145) ; and their 

 causes always lie in disorders of nutrition, especially in a 

 disturbance of the process of taking in oxygen through the blood. 

 If, e.g., insufficient oxygen is carried to the cell, or if for other 

 reasons its capacity of receiving oxygen is diminished, the fat, 

 which probably in most cells appears in traces, is not burned, i.e., 

 oxidised, as happens normallj', but is stored up and accumulates in 

 quantity. For this reason also in habitual drinkers and after 

 phosphorus-poisoning, where as a result of the ingested alcohol or 

 phosphorus the income of oxygen is diminished, a considerable 

 fat-raetamorphosis of the tissues, especially of the liver-cells, 

 always takes place : and pathology recognises a \vhole series of 

 cases where fat-metamorphosis can be traced to the sam.e 

 causes. It is highly probable that in all processes of fat- 

 metamorphosis the fat originates from the decomposition of 



Fig 144. — Fat-metamorphosis in the foi-ma- Fia. 145. — Fat-metamorphosis of cardiac 



tion of milk in the lobes of the lacteal muscle-cells ; the granules in the cells 



glands, (After Virchow.) consist of fat. (After Ziegler.) 



proteid. It is known that in the decomposition of the proteid- 

 molecule both nitrogenous and non-nitrogenous complexes of 

 atoms appear. Moreover, it has been seen,^ that fat can be formed 

 from proteid ; and Leo ('85) has shown in the case of fat-meta- 

 morphosis after phosphorus-poisoning that the fat originates within 

 the body. Since now, thirdly, it has been found that the excretion 

 oi urea is considerably increased after phosphorus-poisoning, the 

 conclusion is justified that after phosphorus-poisoning proteid is 

 decomposed in greater degree, and that the non-nitrogenous 

 complex of atoms that arises during the decomposition is the fat 

 deposited in the cells, while the nitrogenous portion is transformed 

 into urea and given off to the outside. The origin of fat, at least 

 in all fat-metamorphoses, must be regarded as wholly analogous. 



The phenomena of miicous metainorpliosis form a complete 

 counterpart to those of fat-metamorphosis. As in the latter fat, 

 so in the former mucus, is formed from the living substance of the 



1 Cf. p. 163. 



