stances will be colored violet or black, and nematode eggs will be 
colored black with a light areole where the shell shows at the peri¬ 
phery. Various stains have been used to stain plant material and 
leave worm eggs standing out against a stained background. Among 
Fig. 75. A diatom, Navicula sp. x 500. From Campbell, 1902. 
these stains are magenta, used by Giles, methyl green, used by Looss, 
Orange-G, used by Taylor, and gentian violet, used by Fauntleroy and 
Hayden. It is rarely necessary to resort to such elaborate technic to 
determine whether material is parasitic if one has been properly in- 
Fig. 76. A pelagic diatom, Planktoniella sol, viewed from above, x 125. From 
Campbell, 1902, after Schuett. This is actually disk-shaped. 
structed in the subject of making fecal examinations, but when one 
must learn the art unaided, such devices are sometimes of value. 
There should be little occasion to confuse the seeds of the higher 
plants with parasite eggs, as the seeds are usually much larger and 
are densely opaque. A distinctive structure of seeds is the micropyle, 
the aperture at which the young plant starts to grow from the seed. 
However, such confusion does arise and the Veterinary Record for 
October 3, 1914, reports a case in which small brownish objects in the 
feces of a patient were regarded as parasite eggs and subsequently 
found to be vanilla seeds, the patient being accustomed to drinking a 
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