66 



HENRY LESLIE OSBORN. 



mm. thick, enclosing a central mass, dark yellowish-brown and 

 hard, as if perhaps chitinous, of a diameter of 0.5 mm. By 

 manipulating the cysts with little knives made from specially 

 ground needles I found it possible to extract from them a very 

 immature fluke (see Fig. 2) recognizable as B. cornuta by its oral 

 sucker. A pair of eyes is present, but the inner organization 

 showed no traces. I suppose the dark granular mass at the pos- 

 terior end to be a supply of food for the developing worm. 

 Some of the cysts differ by having in place of the hard grandular 

 inner cyst a thin homogeneous covering, enclosing a worm so 



o.p 



o.i mm 



ex.po 



FIG. 3. Sagittal section, cam. luc. X 60. 

 o.p. , oral papilla ; pph,, pre-pharynx. 



dr., cirrhus ; ex.bl., excretory bladder ; 



much more advanced in development, that the alimentary and 

 excretory systems ^were formed and the genital organs well 

 advanced. In early August cysts having a diameter of I mm. 

 or over were found which contained fully matured worms, con- 

 taining embryos numerous enough to impart a distinctly brown 

 tinge to the parent. These facts are of very considerable interest, 



