528 



ORGANIZATION OF T^NIA SOLIUM. 



At this time they are also destitute of the numerous short off-shoots, 

 which only appear when the commencing longitudinal extension 

 diminishes the transverse diameter of the worm, and when the trans- 

 verse canals begin to shorten ; and it is only at this time that the 

 formerly dichotomous branchings assume by anastomosis the form so 

 characteristic of this species. 



FlQ. 295. — Hal f-iipe joint of 

 Tarda solium. ( x 2. ) 



Fig. 296. — Half -ripe joint ( 

 T<Bnia laginala, ( x 2.] 



What I have observed regarding the embryonic development of 

 Tcenia solium is in close correspondence with that of the related forms. 

 In the half-ripe eggs, besides the embryo, or the ball of cells which 

 becomes changed into it, there are three large nucleated cells, with 

 granular masses filling up the interspaces between them. These 

 structures are enclosed along with the embryo in an envelope, which 

 is often tailed, and are still to be found when the embryo has become 

 surrounded by its shell. Afterwards most of the cells are destroyed, 

 so that there only remains within the shell-bearing embryo a viscid 

 fluid abounding in granules. This reminds one somewhat of the 

 albumen of a bird's egg, and, like it, is surrounded by a' kind of shell, 



namely, the enveloping membrane. But 

 in the ripe proglottides both the albumen 

 and membrane have generally disappeared, 

 or rather have been resolved into a pulpy 

 substance, which, along with the shell- 

 bearing embryos, form the so-called " eggs 



Fig. 297. — 'Eggs ot Twnia solium, . ^, i i_j_- ■< >, i • i ^n ^i • i. „: 



(>l)with and (J) without primitive of the proglottides, which fill the mterior 



viteUine membrane. ( x i50.) of the uterus. The shell of the embryo is, 



as in Tcenia saginafa, thick and firm, of a brownish colour, and 



covered with countless little rods, but of a rounder shape. Its 



diameter amounts to 0'03 mm., while that of the simple embryo is 



not more than 0'02 mm. 



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