ORIGIN OF CYSTICA AND CESTOIDEA y 65 



wider than they were long, still the development of the sexual 

 apparatus, manifested externally by the presence of irregularly 

 alternating sexual apertures on one side or the other, had already 

 commenced within them. In a few of the most developed pos- 

 terior joints of one individual, I could perceive roundish hard- 

 shelled eggs, which contained the characteristic embryo with six 

 hooks, and in regard to shape, size, number, and arrangement 

 of the investments of the egg, exactly resembled the eggs of 

 the Tcsnia strrata. I must also remark, that in the larger indi- 

 viduals the developed joints were marked, on the upper surface, 

 with transverse wrinkles, which gave their lateral edges a wavy 

 appearance, and that the slightly prominent posterior edge of many 

 of these joints seemed to be faintly and irregularly puckered. 

 Some of the largest individuals had already cast off their hinder- 

 most joints ; in others, the last " scarred" joint was peculiarly 

 altered ; it was much enlarged, but had at the same time taken 

 quite an irregular shape, with blunt projecting angles at the sides ; 

 the sexual aperture at the side, and the small scar on the 

 posterior edge, alone betokening its true nature. 



Sixth experiment. A mongrel of poodle and spaniel, which 

 had devoured five Cysticerci on the 7th June, and twelve on the 

 29th June, was killed on the 25th July, that is eight-and-forty 

 days after the first meal, and six-and-twenty after the second. 

 Out of the seventeen Cysticerci administered, fifteen were again 

 discovered as sexually matured tape-worms; the smallest were 

 from four to nine inches long, the largest from fourteen to twenty- 

 six inches. In these last the posterior joints appeared already to 

 be longer than they were broad. In other individuals the less 

 elongated posterior joints had a squarish or transversely elongated 

 shape, and upon their exterior surface showed the above-mentioned 

 transverse wrinkles. The hindmost joints were cast off in 

 some of the larger individuals, whilst the rest still possessed 

 the original posterior joint, which was remarkably grown, not 

 being in the least degree inferior in size to the other posterior 

 joints, from which, however, it was essentially distinguished by 

 the small scar on its posterior rounded edge. 



Seventh experiment. From the 21st May to the 5th June, an 

 interval of sixteen days, thirty-one thin-necked Cysticerci were 

 administered to a young fox. On the 13th June he was killed 

 and examined ; but there was not a trace in his intestines of the 

 Cysticerci he had eaten, either in the shape of scolices or of tape- 



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