NEMATODA 197 



that the movements of the parasites will be more sluggish, and 

 their form probably altered owing to irregular contractions and 

 dilatations of their substance changes which may also occasion- 

 ally be observed when embryo-haematozoa are preserved on a 

 glass slide, and they may sometimes be kept alive thus, if in 

 suitable media, for two or three days. When the insect is not 

 examined till the third day, the contained parasites will pro- 

 bably manifest marked signs of disintegration and possibly 

 every indication of life will have disappeared from many of the 

 specimens. After the third or fourth day I have not seen any 

 active specimens of these entozoa in the stomach or in any part 

 of the alimentary canal of the mosquito ; those which remain 

 have undergone more or less fatty degeneration, and are readily 

 stained with eosin, which, as far as my experience goes, is not 

 the case so long as they are alive and active. After the fourth 

 or fifth day it is very rare that traces of any haeinatozoa-like 

 objects can be detected at all, so that it must be inferred either 

 that they have succumbed to the digestive action of the insect's 

 stomach or been disposed of along with the excreta." An 

 important addendum by Lewis records a fortunate incident 

 as follows : " It was observed that nearly all the mosquitoes 

 captured in one of the servants' houses contained haematozoa, 

 so that the supply of suitable insects in all the stages of their 

 growth became amply sufficient for all requirements. The 

 result of the examinations under these favorable conditions has 

 shown that although the stomach digests a great number of the 

 ingested haematozoa, as mentioned above, nevertheless others 

 actually perforate the walls of the insect's stomach, pass out, 

 and then undergo developmental stages in its thoracic and 

 abdominal tissues." 



I may here observe that Sonsino has instituted a comparison 

 between the embryos of this Filaria and those of Anchylostoma, 

 by which it appears that the former measure 0'218 to 0*330 mm. 

 in length, and those of Anchylostoma 0*430 mm. The haema- 

 tozoa are about forty times longer than broad, and the larval 

 anchylostomes only fourteen times longer. The tail of Filaria 

 is conspicuously longer. 



In the ' Lancet ' for June 22nd, 1878, an announcement 

 appeared from the pen of Mr D. H. Gabb, of Hastings, stating 

 that a patient under his care formed the habitat of Filaria 

 sanguinis hominis ; and in the autumn of the same year a 

 paper which I read to the Linnean Society in the spring 



