T^NTA ECHINOCOCCUS. 275 



may briefly mention, in passing, that Virchow thinks the echinococ- 

 cus vesicles are primarily formed in the lymphatic vessels, whilst 

 Schroder Yan der Kolk thinks that they originally take up their 

 abode in the biliary ducts. 



Turning now to some of the more practically important ques- 

 tions affecting the diagnosis and prophylaxis of hydatid formations, 

 one naturally demands to know in the first instance, what is their 

 relative frequency of residence in the different parts, organs, or 

 viscera of the human body. On this point, from personal observa- 

 tion, no pathologist speaks with more authority than Eokitansky, 

 according to whom their seat is prevalent in the following order : — 

 1. hver; 2. subperitoneal areolar tissue; 3. omentum; 4. mus- 

 cles of the heart; 5. brain; 6. spleen (generally associated with 

 one in the liver) ; 7. kidneys ; 8. lungs ; 9. bones. 



M. Davaine, who appears to have gone over the literature of 

 this subject with extraordinary care, writes as follows (" Traite des 

 Entoz," p. 375) : — " In man the hydatids are found in all the 

 parenchymatous organs, but with a very different degree of fre- 

 quency. The liver, in itself, offers more cases of this affection 

 than all the other organs put together. Often, when the hydatids 

 exist in some distant parts, they are found at the same time in the 

 liver. The lung takes the second place as regards the frequency 

 of the hydatids ; they are, again, rather common in the spleen, the 

 kidneys, the omentum, (and) the brain. "We are in possession of 

 some examples from the spinal canal, from the eye, and also from 

 the bones ; it is scarcely more common to encounter them in the 

 limbs and in the parietes of the chest and abdomen ; the testicle, 

 the ovary, the uterus, and the mamma are very rarely infected." 

 The author then gives an approximatively correct analysis of all 

 the cases quoted by him in his voluminous treatise ; their total 

 number amounting to 373. Their relative frequency of occurrence 

 in the various organs stands as follows (the figures appended 

 indicating the number of cases) : — Liver, 165 ; lungs, 40 ; kidneys, 

 30; pelvis, 26; brain, 20?; bones, 17; parietes of the trunk, 12 ; 



