DISEASES OF THE CIRCULATORY SYSTEM. 77 



of the heart for the most part, sometimes extending 

 through the tricuspid valve into the auricle and even into 

 the superior vena cava, and very generally through the 

 semilunar valves far into the pulmonary artery and its 

 branches." In one case forty-one worms were counted. 

 They are found massed together in a thick bundle, con- 

 sisting of the larger female and the male, which has a 

 long narrow tail curved like a corkscrew. The smallest 

 female measured was seven inches in length. How the 

 parasite enters the circulation has not been ascertained. 

 The position in which the mature parasite is found (in 

 the right rather than left side of the heart) is fortunate, 

 for only the immature embryos, smaller than a blood-cor- 

 puscle, can escape the filtering action of the lungs, whereas 

 unhatched ova or debris resulting from death of the para- 

 site, if they passed into the smallest arteries, would give 

 rise to emboli. Probably tuberculoid disease results 

 occasionally from such bodies becoming entangled in the 

 lungs.* The most frequent ill effect, however, is an 

 interference with the valves of the heart and the capacity 

 of the pulmonary arteries and its branches ; it is never- 

 theless astonishing how large the rope of worms may be 

 without causing death. It is noticeable that death gene- 

 rally results after exertion, such as fighting, when the 

 energetic action of the ventricle may force one or more 

 worms suddenly into the pulmonary artery, or entangle 

 them among the valves. After a day or two, during which 

 there are indications of breathlessness or of failing cir- 

 culation, death may come on suddenly. Hollingham 

 mentions dulness, constipation, absence of fever, frequent 

 vomition, irregularity of the pulse, and frequent " fits " 

 as the symptoms in a case observed by him (' Veterinary 

 Journal,' vol. xiii). 



* Rivolta, when at Turin, was surprised to find embryos of F. immitis in 

 the blood of dogs which had during life presented all the symptoms of dumb 

 rabies, and which, from a clinical point of view, might be regarded as suffer- 

 ing from that disease. He attributes the symptoms to the embolic action of 

 the embryos (1875). He also believes they may cause death by producing 

 pulmonary congestion, or enterorrhagia, or grave hsemorrhagic typhus (' Vete- 

 rinary Journal,' June, 1882). 



