144 ANIMAL PARASITES. 



abdomen, which communicates both with the intestine and the 

 outer world, as for instance when an intestinal fistula exists in 

 him, the passage of individual segments, or series of segments, 

 through the fistula is rendered possible. Whilst I am writing, 

 there is in Dresden a patient, belonging to a good family, 

 from whom proglottides passed through an intestinal fistula 

 in the neighbourhood of the navel. The surgeon who had 

 the dressing of the wound soon found repeatedly elongated thin 

 organisms, which moved about in the matter on the bandages. 

 He brought some of them to P^fessor Richter, who recognised 

 these extraordinary productions as proglottides. 



Nay, there is even another way by which it is possible that 

 the segments may pass outwards, which, rare as it may be, was 

 certainly known to the ancients, namely, the passage of the seg- 

 ments through the urinary bladder. This course also would be 

 intelligible in exceptional cases, as, for instance, if an individual 

 suffering from tape-worm had recto-vesical fistula. 



The passage of the mature segments of tape-worm is not physio- 

 logically connected with any certain time, and if, notwithstanding, 

 they pass more frequently at certain times than at others, neither 

 the moon and its phases, nor any other periodical times, have any 

 influence upon it, but it always depends upon periodical external 

 or internal causes. Thus, for instance, in the case of T&nia 

 solium, it cannot be a matter of indifference that pork is eaten 

 especially at certain times (from October to March). And as 

 the Cysticerci are thus more frequently swallowed by men at this 

 period, and must have become developed three or four months 

 afterwards into Tanice, which are giving off their segments, the 

 months from January to July must also be the favorite months for 

 the passage of the fragments of tape-worms. On the other hand, 

 however, these months are by no means the only ones in which 

 pork is eaten, and therefore segments of tape-worms may also 

 make their first appearance from an individual in other months. 

 To this we must add the circumstance that when once a tape- 

 worm has become mature, it constantly forms segments which 

 are destined to pass out, and this may continue through the 

 whole year. For how many years this may be possible cannot 

 be stated, as we do not know how long any tape-worm is capable 

 of existing in the same human intestine. That this may possibly 

 be for a considerable number of consecutive years, is a supposi- 

 tion necessitated by the practical experience that we constantly 



