PARASITES OF THE CIRCULATORY SYSTEM 115 
blood-stream. The symptoms may hence be those of 
enteritis or hematuria. Man may be affected with the 
parasite obtained from cattle. 
The means of infection in cattle is the drinking of 
impure water. 
Cystic forms of various tapeworms are sometimes 
seen in the heart tissue (cf. Cysticercus cellulose, 
Cysticercus bovis, Cysticercus tenuicollis, Echinococci). 
The dog may be infested with several Hematozoa. 
Hematozoon Lewisi.—This is the embryonic stage 
of a Filaria, about zz inch in length. They may be 
found in drops of blood taken from the capillaries of 
dogs in India, China, and the East. They have a fine 
body, drawn out into a very thin tail. According to 
some observers (Grassi, Lewis), when observed micro- 
scopically, they have the power of attaching themselves 
by the buccal end to the cover-glass, and freely moving 
the body. This is not evident in the next-mentioned 
parasite. 
Filaria Immitis.—This is a white filiform worm, with 
the anterior end only slightly larger than the posterior, 
both being somewhat blunt. The tail is spiral and 
carries two wings. The average length is about 8 inches, 
the females being the larger. 
The parasites inhabit the right ventricle of the heart 
(often twined round the chorde tendinez) and the 
pulmonary artery of dogs in Denmark, Italy, China, 
etc. 
The embryos inhabit the peripheral vessels, particu- 
larly at night, and the large vessels of the body by day. 
They much resemble Haematozoa Lewist. 
SympToms.—Often these are absent. 
Usually the symptoms are those of chronic valvular 
disease, with dyspnoea, cough, and dropsy. Embolism 
of various vessels, such as those of one limb, is not 
uncommon. Symptoms resembling those of rabies 
