THE LAWS OF PROTOPLASM I4I 



into the blood of man helps to neutralize the 

 poison which the germs have set free into the 

 blood. If the body is able to recover from this 

 disease without the use of antitoxine, it is believed 

 that it has been able to manufacture its own anti- 

 toxine. That this is probably the correct inter- 

 pretation, the study of "carriers" seems to prove. 



After a person recovers from diphtheria and is 

 able to go about his usual duties, he may have a 

 number of active diphtheria germs in the nasal pas- 

 sages or throat. In sneezing or coughing, these 

 are set free in the air. If they find lodgment in 

 the nose or throat of another, they may cause 

 him to have diphtheria. The first man has become 

 immune to the poisons which now cause the second 

 man to have diphtheria. Diphtheria epidemics in 

 schools are frequently caused by the germs being 

 discharged from an apparently well child. 



In the case of several diseases, the body is im- 

 mune from subsequent attacks. In a figurative 

 sense, we might say that the cell remembered the 

 struggle that it had to throw off the poison and 

 prepared defenses against a second attack. But 

 not all people are protected from a second attack 

 of whooping cough, for example, nor are those 

 who are immune at one time necessarily immune 

 for all time. The general condition of the body 

 has a large Influence upon man's ability to resist 

 disease. Is he well nourished? Are the muscles 



