DISTURBANCES OF METABOLISM. 169 



in many of these diseases the causal organism has not yet been 

 isolated. We. have, however, the important fact that corre- 

 sponding skin eruptions may be produced by poisoning with 

 certain drugs. In the nervous system degenerative changes 

 have been found in diphtheria, both in the spinal cord and in 

 the peripheral nerves, and have been reproduced experimentally 

 by the products of the diphtheria bacilli. There is also experi- 

 mental evidence that the bacillus coli communis and the strepto- 

 coccus pyogenes may, by means of their products, produce areas 

 of softening in the spinal cord, and this may furnish an explana- 

 tion of some of the lesions found clinically. It is also possible 

 that some serous inflammations may be produced in the same 

 way. 



B. Disturbances of Metabolism, etc. It will easily be real- 

 ised that such profound tissue changes as have been detailed 

 cannot occur without great interference with the normal bodily 

 metabolism. General malnutrition and cachexia are of common 

 occurrence, and it is a striking fact found by experiment that 

 after injection of bacterial products, e.g. of the diphtheria bacil- 

 lus, a marked loss of body weight often occurs which may be 

 progressive, and ultimately lead to the death of the animal. In 

 bacterial disease assimilation is often imperfect, for the digestive 

 glands are affected, it may be, by actual poisoning by bacterial 

 products, it may be by the occurrence of fever. The fatty de- 

 generations which are so common are indicative of a breaking 

 down of the proteid molecules, and are associated with increased 

 urea production, while the degeneration of the kidney epithe- 

 lium renders the excretion of waste products deficient or im- 

 possible, and this is not infrequently the immediate cause of 

 death. But of all the changes in metabolism the most difficult 

 to understand is the occurrence of that interference with the 

 heat-regulating mechanism which results in fever. The degree 

 and course of the latter vary, sometimes conforming to a more 

 or less definite type, where the bacilli are selective in their field 

 of operation, as in croupous pneumonia or typhoid, sometimes 

 being of a very irregular kind, especially when the bacteria 

 from time to time invade fresh areas of the body, as in pyaemic 

 affections. The main point of interest regarding the develop- 

 ment of fever is as to whether it is a direct effect of the circu- 

 lation of bacterial toxins, or if it is to be looked on as part of 



