602 Introduction to the Study of Science 



has been gained of the chemical nature of antitoxins produced 

 by the bodily cells in resisting infective germs, of the toxins 

 formed by the bacteria, and of the new compounds resulting 

 from the union of these two substances is of great practical 

 importance. It throws light upon the natural processes and 

 elements that wage war against invading microorganisms and 

 are active during recovery from disease. It makes possible 

 the artificial preparation and efficient use of antitoxins both 

 for prophylactic and for curative purposes. This constitutes 

 one of the most noteworthy achievements of modern medicine. 

 To-day artificial antitoxins are prepared and used for all bac- 

 teria that produce soluble poisons, poisons, that is, which 

 spread through and affect all surrounding substance, gland, 

 tissue, or blood. They have proved to be especially successful 

 in curing diphtheria and in preventing tetanus ; and promise 

 to become equally valuable in treatment of epidemic dysentery, 

 rabies, and other diseases. There is another point strongly 

 emphasized by this knowledge of the processes and the sub- 

 stances involved in recovery from disease. It is that the body 

 should have such hygienic care and medical treatment as will 

 enable it to marshal all its natural energies of defense against 

 the invading organisms, their toxic products, and the resulting 

 diseases. 



SUMMARY 



Infectious diseases are due to microorganisms; non-infectious to 

 various causes, as faults in diet, and in amounts of exercise and rest. 



Pathogenic germs are transferred directly or indirectly from per- 

 sons or animals. They may enter the body through cuts or abrasions 

 in the skin, or insect bites, or through the mucous membrane. 



Immunity to any disease may be natural, as an inherited quality. 

 It may also be acquired either from having recovered from the disease, 

 or from having been vaccinated against it. 



The germ, or infective organism, to produce the disease, must 

 not only find lodgment in an individual, but develop, multiply, and 

 evolve toxins that are not neutralized by the body. 



Vaccination, as against smallpox and typhoid fever, is the inoculation 



