Hcsmatozoa of the Dog. 415 



Development. The life history of the worm is imperfect. It 

 attains sexual maturity in the blood, and there deposits its ova 

 and embryos. Manson noted a habit of these embryos to abound 

 in the superficial blood vessels during the night and retire to the 

 large vessels of the chest and abdomen during the day , after the 

 manner of the filaria sanguinis hominis. Neumann supposes 

 that these embryos are sucked in by mosquitoes, fleas, or lice, on 

 the death of which they escape into water, where they pass 

 through a necessary intermediate stage of development, to be 

 again taken in by the dog in drinking. This again agrees with 

 the habit of the filaria sanguinis hominis, but for the filaria 

 immitis absolute proof is still wanting. Most of the embryos 

 taken in by fleas and lice perish in their intestine (Grassi). The 

 filaria immitis, however, prevails especially in regions where the 

 ground is low and wet and where there is every opportunity for 

 an external existence of the worm in water or some aquatic host. 



Lesions. The number of worms found in one patient may be 

 from five to several hundred (Megnin) and in exceptional cases 

 all are of one sex. Usually there are two females to one male. 

 They are fouud wound around the coluynncs carnce and cord<z 

 tendinee impeding the heart's movements, in the venae cavse an- 

 terior and posterior and in the pulmonary artery and its ramifica- 

 tions in the lungs. Cardiac hypertrophy, and right cardiac en- 

 gorgement are not uncommon, and pulmonary congestion has 

 been noted especially on that side in which the parasites are 

 found. Again the worms have been found in other organs, 

 notably the liver (Leidy), the subcutaneous connective ti.ssue 

 (Ercolani, etc.) in which latter they are smaller than in the heart, 

 yet sexually mature (I^anzilloti-Buonsanti). The same writer 

 has found the embryos in snbpleural nodules like millet-seeds or 

 peas, and the coincident haemorrhages and exudations found in 

 other organs such as the spleen (Reuther), the kidneys and blad- 

 der (L,eidy), the anterior and posterior cavse (Schuppert, I^abat) 

 the pleura and pericardium, suggest their presence and the oc- 

 currence of coagulation, embolism, and congestion as a conse- 

 quence. 



Symptoms. These are exceedingly varied, according to the 

 part attacked. The impaired heart action determines catarrhs of 

 the stomach, bowels, urinary bladder or lungs, which may be 



