EFFECTS CAUSED BY THE PRESSURE OF THE TUMOUR. 645 



specific influence on the organism which shelters it. It might cer- 

 tainly be supposed that the process of immigration would cause dis- 

 turbances of this kind (and indeed Klichenmeister has lately expressed 

 himself of this opinion), but these could only result from an unusually 

 abundant infection, and this is almost excluded by the nature of the 

 adult Tcenia. In the next place, the irritation which the developing 

 parasite produces in its surroundings, has as a rule no further conse- 

 quences than the formation and thickening of the wall of the cyst 1 

 and the displacement of the surrounding tissue. 



The danger of the Echinococcus disease, however, arises from the 

 effects of the pressure of the growing parasite, and this pressure is 

 moreover always increasing, since the growth of these worms, and par- 

 ticularly of the hydatid form, which is by far the most frequent in man, 

 is almost unlimited. In this respect the Echinococcus is exactly like 

 certain tumours, with which it was classed until the end of the last 

 century, and for which (at least during life) it may be still easily 

 mistaken. 2 



This also explains how it is that, when the Echinococcus remains 

 small or dies early, it usually causes so little annoyance that its pre- 

 sence is perhaps only discovered upon post mortem examination. The 

 frequency of these latent Echinococci may be seen from the fact that 

 of twenty-two cases which Bocker collected from the results of the 

 Berlin Charite Hospital, only nine had been diagnosed during life. 

 Among twenty-three cases of Echinococcus, Frerichs found eleven 

 latent, and Neisser found as many as thirty-one among forty-seven. 



The first and chief consequences of the pressure are that the adjoin- 

 ing vessels and glandular passages are compressed and rendered impas- 

 sable to a varying extent. (Edema, varicose veins, and congestions of 

 various kinds, are thus very frequent accompaniments of Echinococcus. 



This pressure is most constantly manifested when the parasite is 

 developed in cavities with more or less firm limits, as, e.g., in the 

 thorax, where it occasions the most serious dyspnoea, or in the pelvic 

 cavity, and especially in Douglas' pouch, where its pressure both 

 anteriorly and posteriorly considerably impedes the passage of the 

 urine and the expulsion of the faeces. In women Echinococci thus 

 situated sometimes act as such hindrances to delivery that it can only 

 be accomplished after the puncture of the bladder. 



1 We know cases in which this cyst wall (only in consequence of repeated inflamma- 

 tory processes) had attained a thickness of several centimetres. 



* Even distinguished authorities upon abdominal tumours, such as Spiegelberg, Dum- 

 reicher, Baum, and Esmarch, have made mistakes of this kind, and while endeavouring 

 to perform ovariotomies, have found to their astonishment, instead of the degenerated 

 ovary, an Echinococcus. As a rule a simple puncture will be sufficient to avoid such an. 

 erroneous diagnosis. 



