deposited by the female worm and as found in the feces, the ascarid 
eggs (Ascaris, Belascaris, Toxascaris, etc.) show little trace of in¬ 
ternal development and some little time is necessary for the formation 
of the embryo in the shell. Where eggs are found containing developed 
embryos, it may be taken as evidence that they are not actually from 
fresh feces but from older material which may contaminate fresh feces 
collected from an area not properly cleaned before the collection of the 
fresh sample. 
Fig. 11. Trichuris depressiuscula. Egg. x 340. From Riley and Fitch, 1921. 
The hookworm eggs are elliptical, thin-shelled and usually found 
with the contents in a state of segmentation. In Ancylostoma caninum 
of dogs, cats and foxes, the eggs (Fig. 10) are 74 to 84 microns long 
by 48 to 54 microns wide. In Uncinaria stenocephala of dogs, cats 
and foxes, the eggs are 63 to 67 microns long by 32 to 38 microns wide. 
Whipworm and hairworm eggs are characteristically lemon-shaped, 
Fig. 12. Dioctophyme renale. A, egg showing shell surface with markings. B, egg 
showing embryo and optical section of shell, x 250. From Railliet, 1893. 
with an opercular plug at each end. In Trichuris depressiuscula 
(T. vulpis) of the dog and fox, the eggs (Fig. 11) are 72 to 80 microns 
long, according to Railliet, or 77 to 86 microns long, according to 
measurements of American material, by 37 to 40 microns wide. In 
T. campanula of the cat, the eggs are 72 microns long by 34 microns 
22 
