140 BIOLOGY FOR BEGINNERS 



used. This is especially true in treatment of diphtheria. This 

 antitoxin is obtained from horses, which have acquired immunity 

 by having been inoculated with frequent doses of the diphtheria 

 toxin, till their blood has an excess of antitoxin, which may then 

 be drawn off, prepared and injected into the system of the patient 

 early in the attack, thus supplying more antitoxin than the child 

 might be able to produce in its own cells even after days of illness, 

 if at all. 



Another dreadful disease which is successfully treated in this 

 way is tetanus or lockjaw. This is a frequent result of wounds in 

 which dirt gains entrance, such as Fourth of July pistol injuries, 

 and cuts on the feet, which are apt to be infected from the soil. 

 It is not the fact that the nail is rusty which makes it dangerous 

 to step on, but that a rusty nail generally is a dirty nail, and may 

 infect with disease. 



Germicides. Other means of destroying bacteria are by the 

 use of antiseptics, and disinfectants which are chemical substances 

 that destroy or hinder the growth of disease germs. Some valuable 

 antiseptics which should be used, even in small wounds, are iodine 

 hydrogen peroxide, alcohol, ichthyol ointment, 4 per cent solution 

 of carbolic acid or 10 per cent solution of potassium permanganate. 

 Boric acid, camphor, thymol, and even common salt are useful in 

 some cases. 



Disinfectants are chemicals used to kill germs outside the body, 

 as in case of clothing, utensils, bedding, and rooms that have been 

 occupied by persons ill with infectious diseases. Bichloride of 

 mercury, a dangerous poison, is valuable for disinfecting the hands 

 or washing woodwork; dilute carbolic acid may be used for the 

 hands, clothing, or bedding. Formaldehyde solution may be simi- 

 larly used, though sometimes injurious to the skin; several coal 

 tar products such as cresol, lysol, cresoline, etc., are said to be as 

 efficient as carbolic acid, and less dangerous. For outdoor disin- 

 fection of cesspools, garbage cans, or privies, chloride of lime, or 

 freshly prepared milk of lime, may be used, the former being es- 

 pecially useful in typhoid fever. To disinfect a room following in- 

 fectious disease, all woodwork should be thoroughly scrubbed with 



