TECHNIQUE. 



41 



become motionless at room temperature after an hour 

 or so, it is not unusual to observe motility in these 

 parasites in specimens of feces which have been col- 

 lected for several hours. If the amoebae are not 

 motile the gentle warming of the slide will often 

 restore motility, provided degeneration of the para- 

 sites has not occurred. Even when the amoebae are 

 motionless it is not difficult, for one accustomed to 

 observing them, to distinguish them from other bodies 

 occurring in the feces. Many observers claim that 

 a diagnosis of the presence of amoebae in feces should 

 never be made unless the organisms be motile. 

 While this is valuable advice for the novice in this 

 line of work, it is certainly true that by one who has 

 studied these organisms, they can be easily recog- 

 nized when motionless, provided the feces has not 

 been kept so long as to have led to degenerative 

 changes in the amoebae. 



In making fresh preparations it is always well 

 to dilute a loopful of the stool with normal salt 

 solution or distilled water. One of the most frequent 

 mistakes made in examining such preparations is the 

 use of too thick a preparation. One should not be 

 satisfied with the examination of a single slide, but 

 should thoroughly examine at least six or eight 

 preparations before a negative result is reported. 



The hanging drop method is often valuable in 



