

A CHAPTER ON MITES. 311 
oblong oval, and contracted just behind the middle. When 
fully grown it measures from a quarter to half an inch in 
length. "We have received it from Missouri, at the hands 
of Mr. Riley, and Mr. J. A. McNiel has found it very 
abundantly on horned cattle on the western coast of Nica- 
ragua. We now come to the genus Acarus (Tyroglyphus), 
of which the cheese and sugar mites are examples. These, 
and their allied forms, are among the most lowly organized 
of the Arachnids, and seem to connect the spiders with the 
Crustacea, the sea-spiders (Pycnogonids) bearing a remark- 
able resemblance to certain mites. Some species of Acarian 
mites have been found in the lungs and blood-vessels, and 
even the intestinal canal of certain vertebrates, while the 
too familiar itch insect lurks under the skin of the hand and 
other parts of the body of uncleanly human bipeds. 
Many people have been startled by statements in news- 
papers and more authoritative sources, as to the immense 
numbers of mites (Acarus sacchari, fig. i 
63) found in unrefined or raw sugar. 
According to Prof. Cameron, of Dublin, 
as quoted in the “Journal of the Frank- 
lin Institute,” for November, 1868, “Dr. 
Hassel (who was the first to notice their 
general occurrence in the raw sugar sold . 
In London) found them in a living state 
in no fewer than sixty-nine out of sev- 
enty-two samples. He did not detect them in a single spec- 
imen of refined sugar. In an inferior sample of raw sugar, 
examined in Dublin by Mr. Cameron, he reports finding 
five hundred mites in ten grains of sugar, so that in a 
pound's weight occurred one hundred thousand of these lit- - 
tle ereatures, which seem to have devoted themselves with 
a martyr-like zeal to the adulteration of sugar. They appear. 
as white specks in the sugar. The disease known as gro- 
cer’s itch is, undoubtedly, due to the presence of this mite, 
Which, like its ally the Sarcoptes, works its way under the 

