132 
Accidental or Facultative Parasites 
Tyroglyphus siro, and related species, have been found many 
times in human feces, under conditions which preclude the explana¬ 
tion that the contamination occurred outside of the body. They 
have been supposed to be the cause of dysentery, or diarrhoea, and 
it is probable that the Acarus dysenteries of Linnaeus, and Latreille, 
was this species. However, there is little evidence that the mites 
cause any noteworthy symptoms, even when taken into the body 
in large numbers. 
Histiogaster spermaticus (fig. 152) is a Tyroglyphid mite which 
was reported by Trouessart (1902) as having been found in a cyst 
in the groin, adherent to the testis. When the cyst was punctured, 
it yielded about two ounces of opalescent fluid containing spermatozoa 
and numerous mites in all stages of development. The evidence 
indicated that a fecundated female mite had been introduced into 
the urethra by means of an unclean catheter. Though Trouessart 
reported the case as that of a Sarcoptid, Banks places the genus 
Histiogaster with the Tyroglyphidae. He states that our species 
feeds on the oyster-shell bark louse, possibly only after the latter is 
dead, and that in England a species feeds within decaying reeds. 
Nephrophages sanguinarius is a peculiarly-shaped, angular mite 
which was found by Miyake and Scriba (1893) for eight successive 
days in the urine of a Japanese suffering from fibrinuria. Males, 
.117 mm. long by .079 mm. wide, females .36 mm. by .12 mm., 
and eggs were found both in the spontaneously emitted urine and in 
that drawn by means of a catheter. All the mites found were dead. 
The describers regarded this mite as a true endoparasite, but it is 
more probable that it should be classed as an accidental parasite. 
Myriapoda 
There are on record a number of cases of myriapods occurring as 
accidental parasites of man. The subject has been treated in detail 
by Blanchard (1898 and 1902), who diserrssed forty cases. Since 
then at least eight additions have been made to the list. 
Neveau-Lamaire (1908) lists thirteen species implicated, repre¬ 
senting eight different genera. Of the Chilognatka there are three, 
Julus terrestris, J. londinensis and Polydesmus complanatus. The 
remainder are Chilopoda, namely, Lithobius forficatus, L. malenops, 
Geophilus carpophagus , G. electricus, G. similis, G. cephalicus, Scutigera 
coleoptrata, Himantarium gervaisi, Cluetechelyne vesuviana and 
Stigniatogaster subterraneus. 
