101. ANIMAL PARASITES. 



eat them with the salad, and thus introduce the germ of the 

 Boihriocephalus into our bodies. AVe certainly, as we have 

 already stated, adopt this mode of infection for the cystic worms 

 which occur in the human body, as, for instance, for Cyslicercus 

 celluloses and tenuicollis, and perhaps for the Echinococci (to 

 which, however, Yogt does not ascribe this course), but certainly 

 not for mature Cestoidea. For even with the Bothriocephali we 

 must assume a migration of the embryos into other animals, and 

 not a development of all the stages in the same intestinal canal. 

 I willingly admit, however, that so long as the six embryonal 

 hooklets are not found with ease and certainty in Bothriocephalic 

 latus — and this I have not succeeded in doing, although I have 

 spent hours in the examination of both fresh and spirit specimens — 

 we have no incontrovertible proof that the embryos of Bothrio- 

 cephalus must perform an active migration through the tissues of 

 their host. But even if there were no six hooklets attached to 

 the young of this cestode worm, the above-indicated, passive 

 migration of the embryos into the intestine of another animal, 

 and their conversion in this intestine into an asexual band-like 

 scolex, seems to me at present much more probable than the 

 development of all the grades in the same intestine, on account 

 of the dissimilarity which exists between the embryos and their 

 parents. For these reasons I must, for my own part, admit 

 that Yogt's hypothesis is still equally untenable, with all the 

 others which have been set up regarding the production of Boih- 

 riocephalus. 



Physiology. — According to Eschricht, the vital manifestations 

 of Boihriocephalus , and its reactions with chemical and mechanical 

 irritants, are more sluggish than those of Tania solium. I have 

 never, myself, seen a perfectly fresh Boihriocephalus. The 

 adhesion is always effected by the two sucking pits, although 

 Seeger-Wundt also states that this takes place by means of a 

 small umbiliciform depression (Sauyflacht) of the apex of the 

 head, which is certainly possible if a frontal sucker could actually 

 be detected in this little pit. The small number and less perfect 

 development of these sucking organs, as compared with those of 

 the T(eni(E, at once explains why Bothriocephalic latus is expelled 

 with such remarkable ease. 



Eschricht and others have already proved the power of im- 

 bibing fluids possessed by the bodies of the Bothriocephali and all 

 Cestoidea. Transudation takes place distinctly by contact with 



