1894.] infested with Filaria immitis. 213 



There seems to be however no doubt according to the researches 

 of Grassi (3) that the Haematozoa of Lewis have their second 

 host in the dog-flea, Pulex serraticeps, and have nothing to do 

 with the larvae of the F. immitis, although they closely resemble 

 them. The former have a curious habit of hanging themselves by 

 means of their oral aperture on to the cover slips or glass slides, and 

 at the same time swelling out their anterior end : by this habit 

 they can be easily distinguished from the embryos of F. immitis. 

 These are also invariably much more numerous in the blood of the 

 dog than the Haematozoa of Lewis. Grassi found the embryos 

 of F. immitis in three dogs which he dissected in Milan, and in 

 two of which he found the heart full of adult Filariae ; the third 

 owing to an accident he was unable to examine. Two others 

 which he was able to dissect later had embryos in the blood, 

 adults in the heart, and more fully developed embryos under the 

 skin : at the same time he investigated more than 300 fleas 

 gathered from the dogs he had killed and dissected, but found 

 no evidence that they formed the second host of this parasite as 

 was at one time thought. 



Galeb and Pourquier (2) found the same embryos in the blood 

 of a gravid bitch whose heart was full of the adults ; they also 

 found similar embryos in the blood of the foetal puppies, and 

 satisfied themselves that the latter were infected from the 

 mother, and that the embryos pass from the blood-vessels of 

 the uterine walls into those of the foetus. 



Grassi's researches render it highly improbable that the flea is 

 the second host of F. immitis, and he points out that the parasite 

 occurs only in such districts as are very well supplied with 

 streams, marshes etc. ; and further that the parasite is most 

 common in such dogs as are used for sport, and which habitually 

 drink water from marshes, ditches and streams, and he concludes 

 from this that we must look for the second host of F. immitis 

 amongst the small freshwater Crustaceans or Molluscs. 



It is obvious that the presence of such a mass of worms in the 

 heart and large vessels, as our specimen shows, must be accom- 

 panied by very serious functional disturbance of the circulatory 

 system, which must ultimately end in the death of the host. The 

 symptoms which the presence of the parasite call forth are thus 

 described by Mrs Towne (6) : " I watched my two remaining dogs 

 closely. They were a large Newfoundland (mixed) and a small 

 terrier. Both had the peculiar cough, which was excited by any 

 movement, especially after sleeping. It always ended, after a few 

 coughs, in a violent effort to bring something up from the throat. 



The two dogs had another symptom. When they began to 



run violently, as at hogs, or a strange dog, they fell down, became 

 stiff and insensible, but in a short time would get up and resume 



