THE ANATOMY OF TKOCTES DIVINATORIUS MUELL 
Euth Chase Noland 
Introduction 
The internal anatomy of Troctes divinatorius has never been 
carefully worked out, though the insect has frequently been de¬ 
scribed as a not uncommon household pest. In 1818 Nitzsch (18) 
published a description and figures of the digestive tract and re¬ 
productive organs of an insect which he called the book louse, 
Psocus pulsatorius. In a number of ways my descriptions differ 
from his, and it is probable that the insect which I have had is a 
different species, although of the same genus, for the generic names 
Psocus, Troctes, and Atropos have all been used in reference to the 
genus to which the book louse belongs. Since the time of Nitzsch, 
the only work which has been done on the book louse from an 
anatomical point of view has been that on the mouthparts, and is 
very little. However, considerable study has been made of the 
mouthparts of a closely related family, the Psocidae. This has 
been done by Burgess (6), Hagen (15), and others and has been 
of interest largely because of the light it throws on the relation¬ 
ships of these to other insects. 
The studies made here of Troctes are based on examinations of 
hundreds of individuals in whole mounts, longitudinal, and cross 
sections and in dissections made in glycerine or in balsam under 
the dissecting microscope. The small size of the specimens, none of 
them more than a millimeter and a half in length, has made neces¬ 
sary the working out of many details by comparison in a large 
number of specimens. For the gross anatomy the micro-dissections 
stained in alum carmine, or haemalum gave most information; 
while the smaller details and histology could only be determined 
from sections. These were stained with Heidenhain’s or Delafield’s 
haematoxylin. A number of fixatives were used, but probably the 
best results came from Carnoy’s I and II, and Kahle, Tower and 
Petrunkewitsch. Very much assistance in the work was given by 
Professor W. S. Marshall, under whose direction it was carried out. 
