292 ENTOZOA. 



have never yet seen a specimen whicli came from an American, 

 nor lias Professor Leidy of PMladelpliia, as lie informs us by letter."* 

 This statement of Weinland is also borne out by the records of 

 other observers. 



Speaking, more precisely, ^vith reference to the actual geographi- 

 cal distribution of this parasite, Leuckart says that, even as regards 

 Em-ope, it is only in certain districts that it is normally present. 

 " Foremost amongst these are the cantons of West Switzerland, 

 with the adjacent French districts. In Geneva, according to Odier, 

 almost a fourth part of all the inhabitants suffer from Bothrioce- 

 phalus. It is also common in the north-western and northern pro- 

 vinces of Russia, Sweden, and Poland. In Holland and Belgium 

 it is likewise found, but on the whole, not so frequently in these 

 first-named countries. Our German fatherland also harbours them 

 in some districts, especially in Eastern Prussia and Pomerania, and 

 there have appeared cases in other places, as in Rhenish Hesse, 

 Hamburg, even in Berlin, these being apparently spontaneous 

 instances. The same has been said of London, St. Malo, Montpe- 

 lier, Rome, Zurich, and so forth." Of course, some of these sup- 

 posed cases are doubtful ; but, at all events, the distribution here re- 

 corded is tolerably accurate, and at the same time highly suggestive. 

 The Bothriocephalus latus would seem, indeed, to be most common 

 where the Tcenici solium is comparatively rare, but from this con- 

 sideration alone we are scarcely entitled to look upon it as a repre- 

 sentative species of the latter. At present, our knowledge of the 

 history of its development is incomplete ; but sufficient, at least, has 

 been accomplished to enable us to set aside the erroneous notions 

 advanced by Vogt and others as to its mode of introduction into 

 the human body. 



Anatomy and Develojpment. — Our information respecting the 

 structure of Bothriocephalus latus is chiefly derived from the writings 

 of Eschricht ; whilst that of its development is obtained from Schu- 



* "Essay rm the Tapcwoiins of Man," p. 59. 



