G. W. McCoy 
221 
which shows very fine transverse striations, but careful examination 
has failed to reveal any indication of a sheath. Within the cuticle is 
a column of nuclei which is more or less completely interrupted by 
several “clear spaces.” 
The nuclei : These are of two varieties: (1) nuclei usually spherical 
and staining uniformly deeply; these are by far the more numerous; 
(2) nuclei that are a trifle larger, somewhat less regular in outline and 
staining less deeply. The fourth nucleus from the tip of the tail is very 
generally one of the latter class. Others are scattered irregularly 
throughout the worm, except in the head and in the other clear areas. 
Clear spaces : The head of the worm is always free from nuclei. 
About one-fourth to one-sixth of the distance from the head toward the 
tail is an area in which nuclei are almost invariably absent. About 
two-thirds of the distance from the head to the tail is a space in which 
cells are few in number. Near the tail, from one-eighth to one-fourth 
of the distance to the head, there is nearly always an area in which 
cells are absent. Some specimens show other clear spaces, but the ones 
mentioned are practically constant. 
Dots or Granules : Almost invariably the clear space lying about 
two-thirds of the distance from the head to the tail will be found to 
contain a large number of fine granules. There are usually a few of 
these bodies, three or four or more, near the extreme front of the head, 
and a small number are often found in the tail. Occasionally granules 
are found in other parts of the worm, but usually they are confined to 
the head and to the clear space, two-thirds of the distance from the 
head to the tail. It was thought at first that these little objects, w’hich 
are only seen in specimens stained with Giemsa stain, were artifacts, 
but their constancy leads to the conclusion that they are part of the 
structure of the worm. 
Head : The head, which is cylindrical, tapers sharply to a flattened 
anterior extremity. The portion devoid of nuclei is usually about one 
and one-half times as long as the diameter of the worm. 
Tail : The tail, which makes up about one-fourth of the length of 
the worm, tapers gently to a rather sharp point. Terminal nuclei in 
the tail are usually oval, the long axis corresponding to the long axis of 
the worm. 
Measurements : The average length of ten specimens was 0 22 mm. 
(extremes, 0T7 mm. and 0'25 mm.). The width is from O'OOoo mm. to 
0‘007 mm., averaging a little less than that of the red blood corpuscles 
of the host. 
V 
