168 OXYURIS-LARViE HATCHED IN THE HUMAN STOMACH, 



OXYURIS-LARV^ HATCHED IN THE HUMAN 

 STOMACH UNDER NORMAL CONDITIONS. 



By N. a. Cobb. 



(Plate VIII.) 



In spite of the fact that Oxyuris vermicular is, the 

 common pinworm or thread-worm parasitic in man, is the Nema- 

 tode that has been lonpjest known and is the one that comes most 

 frequently under the notice of physicians and helminthologists, its 

 life-history has remained incompletely solved. In this respect it 

 is simply illustrative of nearly all the entozoa inhabiting man. It 

 is, for the most part, only by the slow accumulation of occasional 

 bits of evidence, obtained largely by what may be termed accident, 

 that the life-histories of these terrible pests have been brought to 

 their present more or less incomplete state. Pending further 

 observations existing gaps are filled in by more or less probable 

 conjecture. 



Oxyuris v e r m i c u 1 ar is, it is well known, inhabits the 

 large intestine of man, occurring not seldom in thousands, smaller 

 numbers being found in a very large percentage indeed of the 

 subjects for post mortem examination. The worm is not confined 

 to any particular period of life. Though most common in children, 

 scarcely any of whom remain between the ages of two and eight 

 completely free from Oxyuris, it is not less than frequent in 

 older people, even including those of extremely advanced age. 

 Its constant presence and the suffering thereby frequently 

 caused, especially in children, where it often leads to extreme 

 nervousness and irritability to say nothing of its annoying evening 

 attacks, has led to much investigation which is recorded in a 

 literature so abundant as to be equalled by that of but few animal 

 species. Where investigation has failed to throw sufficient light, 

 speculation has stepped in and rendered good service in the labour 

 of completing a rational life-history. 



