PART III.] Anatomical Description of the Encysted Bladder- Worm. 497 



head portion, however, is seen to be still unfolded. Unless the parasite be alive, 

 its further unfolding is attended with considerable difficulty, and can seldom be 

 satisfactorily accomplished, especially if it has been preserved in glycerine. Under 

 other circumstances, the head is readily squeezed out. If a hair be now inserted 

 through the orifice in the outer cyst, and tied round the neck of the completely 

 unfolded worm, this portion may be pulled out, as represented in Fig. 28, and more 



Fig 28. The " head " having been everted, a hair was introduced through the orifice fastened to the " neck " and 



the parasite withdrawn from the " receptaculum." The latter is seen to be continuous with the " neck " itself 

 Magnified about 5 times. 



Fig. 29. — As Fig. 28. The worm completely withdrawn from its enveloping vesicle. Magnified about 5 times. 



completely so in Fig. 29. The part of the worm marked with an asterisk in the 

 woodcut (Fig. 28) is not hollow, as one might suppose from observing that the neck 

 and the hood surrounding it are continuous, for a little membranous tissue stretches 

 across it, differing in structure (more especially by the entire absence of the calcareous 

 corpuscles to be hereafter referred to) from the neck and its reflected continuation ; 

 the little sac acting as a sort of diaphragm, so that air or a coloured solution blown 

 into the outer bladder does not extend up the neck of the worm. This, to the best 

 of my knowledge, is a correct anatomical description of the encysted parasite, the 



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