470 CYSTIC STAGE OF T^ENIA SAGIXATA. 



greatly according to the intensity of the attack. The disease may, 

 indeed, assume another and perhaps less dangerous character. In 

 slight cases it is confined to insignificant and almost non-febrile dis- 

 orders of the digestive and locomotor functions. The animals lose 

 their appetite and liveliness, and grow thin, but in about 

 two months, according to Gerlach's case, or even sooner, according to 

 Simonds and Cobbold, return to the normal condition. If the disease 

 attain full development, it has, not only anatomically, but in its ex- 

 ternal symptoms, an unmistakeable resemblance to miliary tuber- 

 culosis, which results in a sort of typhoid fever. 



In regard to the cause of death of the animals, very different 

 hypotheses have been advanced. I have expressed the opinion that it 

 is to be found in the derangement of the lymphatic system. This was 

 very pronounced in the first of my cases, and might perhaps be referred 

 to the irritation produced by the parasites which had migrated into the 

 lymphatics, and had there developed in large numbers. Although 

 this affection is, as a matter of fact, to be regarded as a constant 

 sign of acute miliary tuberculosis, Hosier thinks my explanation must 

 be rejected. He is of the opinion that death is due to the changes 

 occurring in the heart, which entail disturbances of the circulation 

 and associated dropsical exudations. And lastly, van Beneden regards 

 the death of the animal as the result of a whole series of pathological 

 processes. Besides the well-known alterations in the muscles, con- 

 nective tissue, and heart, he finds signs of peritonitis, and observes 

 clots of blood, not only in the right ventricle and in the left auricle, 

 but also at the bifurcation of the pulmonary artery, in the posterior 

 end of the aorta, and in the circle of Willis. These clots completely 

 close some of the vessels in question, and help to explain how, in the 

 final stages of the disorder, the posterior extremities of the animal 

 become paralysed and insensible. Although a bladder-worm has only 

 once been found in these thrombi, and then in the interior of one in 

 the heart, van Beneden thinks that they are in all cases to be referred 

 to parasites which have, somehow or other, passed into the vascular 

 apparatus, perhaps from the pericardium. He even thinks it possible 

 that the numerous extravasations of blood found in the animal had 

 been caused by migrating worms, and finally expresses the conviction 

 that the embryos pass into the blood-vessels at an early s'tage, and are 

 distributed throughout the body along with the blood. 



But, however the question as to the cause of death may be settled, 

 this much is certain, that it is the ox that harbours the bladder-worm of 

 Taenia saginata, and conveys it to us in its flesh. 



In view of this fact, it is further very surprising that the bladder- 

 worm from the ox, which cannot be very rare, from the frequency 



