280 An Introduction to Medical Mycology 



chief reason for this is the variability of the initial response to the injection 

 of any vaccine in different persons. It appears necessary with each patient 

 to use a control injection of broth, in order to establish a base line. An im- 

 mediate wheal reaction is indicated by a rapid increase in the size of the 

 elevation over that normally present after any intracutaneous injection and 

 by an irregular border, or pseudopods. Itching may or may not be present. 

 When the diameter is below 1.5 cm. 10 minutes after the injection, the 

 reaction is designated as 1 plus. If the diameter is over 1.5 cm. the reaction 

 is designated as 2 plus, and over 2 cm., 3 plus. After 48 hours and after one 

 week the results of the tests are indicated by a cipher for a negative reac- 

 tion; a plus-minus sign for an area of slight erythema approximately 0.5 

 cm. in diameter; 1 plus for 0.5 to 1 cm.; 2 plus for 1 to 1:5 cm.; 3 plus for 

 1.5 to 2 cm., and 4 plus for an elevated area of reaction 2 cm. or more in 

 diameter. 



