TYPHOID FEVER. 501 



must not be too alkaline, as this condition will also cause 

 erroneous results. 



5. Vitality of the Culture. — Except for the fact that 

 dead bacilli are not motile, and hence cannot show a loss 

 of motility as a part of the reactive phenomenon, they 

 are useful for making the test. In fact, the absence of 

 danger of infection, and the convenience with which the 

 sterilized cultures can be sent from place to place to be 

 used by physicians who are unacquainted with bac- 

 teriologic technic, have made Wright and Semple l rec- 

 ommend their use. The reaction is probably physical 

 rather than vital, as it occurs in dead as well as in living 

 organisms. 



6. Peculiarities of Reaction. — It is interesting to note 

 the different forms of reaction, which may be classified 

 as follows : 



a. Cessation of motion (not regarded as typical). 



b. Formation of small aggregations without loss of 

 motion of the free bacilli (not regarded as typical). 



c. Complete cessation of motion and formation of a 

 reticulated agglutinated mass of bacilli covering the 

 whole field. 



d. Complete cessation of motion with the formation of 

 small, fairly uniform aggregations. This usually occurs 

 quickly and is accompanied by distortion of the bacilli. 



e. Complete cessation of motion and the formation of 

 large-sized aggregations, some of which are enormous. 

 The bacilli are shrunken and twisted. (This form of re- 

 action was usually almost instantaneous in its occurrence, 

 and probably indicated that the highest degree of the 

 blood-alteration had taken place. I saw it most marked 

 in a case with two relapses. It is sometimes accompanied 

 by bacteriolysis.) 



f. Rapid agglutination and loss of motion followed by 

 prompt and complete solution of the bacteria. The bac- 

 teriolysis is probably entirely independent of the other 

 phenomena. It may occur in normal blood, but few of 



1 British Med. Jour., May 15, 1897. 



