692 LAURA FLORENCE 
since the longitudinal fibers are gathered in six strands. There is no valve 
between the stomach and the small intestine. } 
Between the small and large intestines is a region, measuring 0.25 
millimeter in diameter, which is characterized by the presence of six 
whitish, oblong-ovate plates imbedded in its wall (Plate LXII, 7). These 
plates, which in sections (Plate LXIT, 8) are seen to extend a considerable 
distance into the lumen of the intestine, are surrounded by a large number 
of tracheae. They have no definite cell structure, their content is 
granular with nuclei scattered throughout, and in some sections irregular 
clefts are present which are evidently not due to mechanical rupture 
and may be definite lumina. No ducts opening into the intestine have 
been seen. With hematoxylin and eosin the groundwork stains an uneven 
pink, and with iron hematoxylin a light grayish brown. Whether these 
plates are modified glands is uncertain. Their inner surface is lined with 
a well-defined intima, and at either end a definite epithelium is represented 
by a few cells in the clefts between the plates, but in the middle of the 
region (Plate LXII, 8) no such cells are to be found. The inner layer of 
circular muscle is present, and the longitudinal muscle consists of six 
bands each made up of six or seven fibers lying in the indentations between 
the plates, but no outer circular layer has been seen. Sikora (1916:67—68) 
calls these plates the “‘ Enddarmdriise,’”’ and objects to the use of the 
name “ rectal glands”’ on the ground that in the louse these plates have 
no connection with the rectum. Her figures of their structure in Pediculus 
vestimentt represent them as much more glandlike than they appear to 
be in Haematopinus suis. Toward the posterior end the cuticula increases 
considerably in thickness and the plates are succeeded by a well-defined 
epithelium. The longitudinal muscle fibers are lost sight of among the 
large circular fibers surrounding the rectum (Plate XLII, 9). This is a” 
short, straight tube leading direct to the anal opening and measuring 
only 0.18 millimeter in length and 0.08 millimeter in diameter. Its wall 
lies in six folds, and it is lined by a thick cuticula which is not very strongly 
chitinized and stains a clear blue with Mallory’s connective-tissue stain 
after fixation in picro-aceto-formol. 
FEEDING AND DIGESTION 
In experimental feeding, when a louse is placed on the arm it crawls 
around and appears to test the surface with the antennae and the sensitive 
