ECHINOCOCCUS ALTRICIPAETENS. 225 



which every one can obtain information for himself in the ordinary 

 manuals of surgery and special pathology and therapeutics. 

 The most useful objective symptoms are, the existence of a sac- 

 culated swelling, which is elastic to the touch and of a peculiar 

 consistency and form, in places where swellings do not usually 

 occur, but where, when these do make their appearance, they are 

 generally Echinococci. The highest degree of probability, we 

 may almost say certainty, that an unopened swelling belongs to 

 a colony of Echinococcus, is attained by the diagnosis, when a 

 swelling occurs in places such as the liver, spleen, kidneys, heart, 

 lungs, breast, throat, or testicles, where Echinococci usually take 

 up their abode, in an individual from whom at the same time 

 Echinococci are otherwise brought to light, either artificially or 

 naturally. We may then with tolerable certainty regard any 

 existing tumours, which also possess the properties of sacculated 

 cysts, as colonies of Echinococcus. One of the most important 

 symptoms for the diagnosis is furnished, although only in 

 particular cases, by percussion. Piorry, as is well known, was 

 the first to call attention to a sensation which is felt by the 

 finger employed in percussion or the hand when pressing, the 

 swelling a sort of trembling (fremissement) which resembles 

 the sensation produced by the clang of a repeater, or a spring- 

 sofa, in the finger that taps it, and which, for the sense of touch, 

 nearly resembles the oscillations detected by the eye when 

 coagulated jelly is set in motion by any cause. This symptom 

 has sometimes been perceived, sometimes not, but it appears 

 certain to me that it can undoubtedly be observed in particular 

 cases, the nature of which, however, is unknown. An attempt 

 has been made to explain this trembling by the fact, that the 

 individual Echinococcus-cysts which swarm about in the mother- 

 vesicle are brought into collision within the latter by the shaking, 

 and this causes the trembling experienced by the finger. In 

 consequence of the confusion which prevails amongst practical 

 surgeons with regard to hydatids and Echinococci, I mvst 

 dwell upon this symptom longer than will perhaps appear jus- 

 tifiable, and I will endeavour here to give an explanation of the 

 hydatid-trembling. In my opinion 



1. This hydatid-trembling can only occur when several gela- 

 tinous, tremulous cysts, which are inclosed within a larger vesicle, 

 also capable of gelatinous trembling, are in any way set in 

 motion. 



