12 TECHNIC 



upon the posterior end of the abdomen and exerting traction 

 upon the head. Instead of wiping with a flat flexible instrument, 

 the abdominal contents may be expressed by rolling forwards 

 under pressure with a needle or fine glass rod. By this means it 

 is possible to eviscerate rapidly the thorax and abdomen and 

 obtain intact in one piece the whole of the alimentary tract, the 

 Malpighian tubules and salivary glands of both types. With 

 care the reproductive organs can also be expressed forwards 

 with little or no injury. (For a description of the anatomy of 

 the human louse see Sikora, 1916, Beihefte 1, Archiv. f. Schiffs- 

 und Tropenhygiene.) 



Between dissections of lice it is imperative to clean with care 

 the instruments so that organisms which are present in one 

 louse are not introduced in the preparations of succeeding lice. 

 When working with typhus infected lice several sets of instru- 

 ments are advisable so that each set may be sterilized in phenol 

 or lysol after using and before washing. 



In handling boxes containing infected lice, louse-proof gowns 

 and rubber gloves were worn. The excreta were regarded as in- 

 fective and were permitted to fall only upon cloths wet with 

 disinfectants. The boxes were opened in large glass crystalliz- 

 ing dishes while under observation by a second person. The 

 lice were removed to glass weighing bottles with the aid of a 

 Zeiss prism magnifying binocular and a count was kept of all 

 saved for dissection. Discarded boxes with possible overlooked 

 immature stages and eggs were immediately placed into a 

 sterilizer. 



In handling lice we have found the prism magnifying bin- 

 oculars indispensable, and have always used very finely pointed 

 yet stout forceps for grasping them by a leg seized close to the 

 body (femur). 



7. STAINING METHODS 



Smear preparations were air dried, fixed for fifteen to twenty 

 minutes in absolute alcohol and stained for a period of three 

 hours or longer in Giemsa's stain diluted in proportions of one 

 drop to one cubic centimeter in distilled water. 



