THE NEMATOID HiEMATOZOA OF MAN. 257 



has been ascertained to exist between the two kinds of embryo 

 filariee in China by Dr. Manson ; but;, according to Dr. Sonsino, 

 those of Egypt^ and apparently those of the Brazils, do not pre- 

 sent this distinguishhig feature. As may be recollected it was 

 mentioned that a distinction also exists between the disease with 

 which the human hsematozoon is associated in the different coun- 

 tries — not a great difference certainly, but, nevertheless, one 

 which should be borne in mind when deciding as to specific dis- 

 tinctions between the parasites. 



It must also not be forgotten that the inhabitants of Brazil 

 and of certain parts of Africa are, as has been known for at 

 least a century, peculiarly liable to be the hosts of tissue-para- 

 sites. The minute thread-like sub-conjunctival filaria [Filaria 

 loo), for example, though from two to six inches in length, has 

 never been accurately described, and its precise thickness is not 

 known yet, although it was discovered by Bajon so long ago as 

 1768,1 and has since been frequently observed beneath the skin 

 and conjunctiva of negroes and other persons. M. Guyon 

 brought it before the notice of the French Academy in 1838, 

 and again in 1864. On the former occasion, the specimens 

 measured 30 — 40 mm., but the helminth described in 1864 was 

 150 mm., in length. It is not quite clear that they belonged to 

 the same species. It is not impossible that the embryos dis- 

 covered by Dr. O'Neill- in a disease of the skin termed Cratv- 

 craiv, on the west coast of Africa, may prove to have been the 

 offspring of some such helminth. 



Again, the minute, thread-like nematoid described in America 

 by Leidy, five inches in length and .^V inch in greatest breadth, 

 is not to be overlooked. It was obtained from the mouth of a 

 child, and derives its name — Filaria hominis oris^ — from this cir- 

 cumstance. 



All these circumstances point to the necessity of exercising 

 considerable caution in arriving at any decision as to the precise 

 relation of any of these as yet obscure parasites. 



With regard to the helmmths discovered by Dr. Bancroft in ) 

 Austraha, I am not in a position to offer an opinion. It has not ( 

 yet been shown that they are blood-worms in the ordinary sense 

 of the term, nor is it known that the individual from whom they 

 were obtained harboured embryo hgematozoa. It is further to be 

 remarked that the affections under which the persons laboured 

 from which they were derived were not of the character of the dis- 

 eases with which these hsematozoa have hitherto been known to 



1 'Comptes Rendus,' t. lix, 1864, p. 745. 

 ^ 'The Lancet,' Feb. 10, 1875, p. 2G5. 



3 'Proceedings of the Academy of Natural Science,' Philadelphia, vol. v, 

 1850-51. 



