306 



Some authorities would have it that the embryo discharged 

 from the proglottis is capable of an immediate conversion into 

 the scolex by burrowing into the soft tissues of the same indi- 

 vidual; but it is more probable that the eggs must first leave 

 the intestine, and mature outside, since scolex seldom occurs 

 together with Ta3nia, and then it is probably accidental. When 

 the mature proglottis is discharged fi"om the intestine, it deposits 

 its eggs in moist earth, on plants, in the water, and so on. These 

 eggs are covered with a very thick membrane, which withstands 

 much pressure between the glasses of a microscope, and they are 

 capable of remaining a long time quiescent, like other pai'asitic 

 ova, till a suitable menstruum is found for their development. 

 That they may pass into the stomach of man and other animals 

 with various articles of diet and drink is unquestioned ; for they 

 are found in water, and on salads and other vegetables, which 

 are eaten without being previously cooked, and sometimes not 

 even washed. 



The genus Ta3nia still requires much study to remove the 

 doubt which rests upon several species. Five or six are known, 

 which find a habitation in man, ( T. solium ; nana ; mediocan- 

 nellata ; ecMnococciis ; T. of Good Hope ; and T. or Bothrioce- 

 phalus latus,) one of which wants the booklets peculiar to the 

 rest. They may be found wanting also in T. solium, in some 

 instances. Of these species the scolices are unknown, with the 

 exception of Cysticercus and Echinococcus. The encysted form 

 of Bothriocephalus may have been confounded with that of T. 

 solium. The joints of this worm are thrown off in chains, and 

 not singly, as with Taenia. Two varieties of the Cysticercus have 

 been observed. 



Of course, after the adoption of the scolex theory, it became 

 interesting to inquire where the Ttenia of the common Echino- 

 coccus had been all this time. Siebold thought that the Ta3nia 

 of the dog was the animal in question ; for he gave the Echino- 

 coccus of animals, ^. veterinorum, to dogs, and at the end of 

 twenty-two days found in their intestine a Taenia with but three 

 joints ; the last one perfect, however, showing that the animal had 

 arrived at maturity. This view was generally adopted till quite 

 recently, when Kiichenmeister showed that the E. veterinorum 

 differed from E. /lominis in the form of its booklets, and he gave 



