486 PARASITES OF ANIMALS 



APPENDIX. The memoirs announced by Dr T. R. Lewis in 

 the January issue of the ' Microscopical Journal/ and referred 

 to at the close of my account of Filaria Bancrofti, having 

 appeared, I fulfil the promise previously made (p. 202). In 

 the few lines at my disposal I may observe that the beautiful 

 brochure (quoted below) supplies fuller details of the results 

 already announced by Lewis in the ( Proceedings of the Asiatic 

 Society of Bengal/ In respect of the nematoid haematozoa, the 

 memoir is chiefly important as confirming Hanson's observa- 

 tions regarding the changes undergone by the Filariae that have 

 been transferred to the stomach of the mosquito, and especially 

 also, as advancing some novel facts in reference to the occurrence 

 of bird's blood-corpuscles, associated with embryonic nematoids, 

 in the same viscus of the insect. The worms are regarded by 

 Lewis as transferred avian haematozoa, a view which gains 

 strength by their comparison with the similar larvae which he 

 had detected in the blood of Indian crows (Corvus splendent). 

 In Egypt, as Sonsino had himself informed me by letter, similar 

 haematozoa are to be found in crows, and avian filariae of this 

 kind were long previously described, as Lewis and Sonsino point 

 out, by Borell, Herbert, Schmidt, and Virchow. Facts of this 

 order undoubtedly complicate matters, and suggest that extreme 

 measure of caution in drawing conclusions, which Lewis himself 

 everywhere displays. 



Respecting the final changes undergone by the mosquito- 

 filariae before their re-entrance into the human body, Lewis does 

 not appear to have gone further than Dr Manson. By rupturing 

 the body of the most advanced larvae, Lewis readily recognised 

 the oesophagus and intestine, but he remarks, significantly, " I 

 have not been able to distinguish any other differentiated viscus 

 in any of the specimens, and certainly, nothing suggestive of 

 differentiation of sex " (p. 83) . In an earlier part of the me- 

 moir Dr Lewis takes objection to my view that the urinary 

 nematoids found by me in a case of Bilharzia are genetically 

 related to Filaria sanguinis hominis. His distinguished coad- 

 jutor, Dr D. Cunningham, also denies the possibility of such 

 relationship. No doubt, if the urinary maternal worm was really 

 oviparous my view is untenable ; but the proved presence of 

 imperfectly formed ovarian ova, in which no trace of embryonic 

 formation was discernible, has forced upon me the conviction that 

 prolapsus and rupture of the uterine tubes of the parent worm 

 had occurred, and that their rupture had occasioned the escape 



