MULTIPLE GENERATIVE PORES. 451 



always as many isolated sets of sexual organs as there were gene- 

 rative openings. 1 



This last fact shows sufficiently that in such cases as the above 

 we have not to deal with joints, as is apparently the case, but 

 with series of joints in which the separation of the individual 

 proglottides has not completely taken place. The slight indivi- 

 dualisation which we have already noted as characteristic of some 

 Cestodes, is here present as an abnormality it is true in 

 species which usually exhibit a very regular segmentation. Such 

 being the case, we can also understand the great length of the 

 joints with multiplied sexual openings, which may in some cases be 

 as much as 15 cm., as in Colin's piece, but the length of the joints 

 is not usually so great as one might infer from the number of 

 proglottides united, judging by their genital pores. The varying 

 degree in which these openings are approximated gives rise to many 

 differences. A portion of a worm with two genital openings had, for 

 example, a length of 18 rnm. instead of about 20, while another with 

 five was only 28 mm. long instead of about 50. 



The case is quite different when two genital openings occur in a joint 

 opposite one another on the same level. Here one finds behind each 

 opening a set of male and female ducts, with cirrhus-pouch and vesi- 

 cula seminalis, but the reproductive organs proper are as usual, the 

 two vaginae passing into a common shell-gland, and into a single uterus. 



As yet I have seen this malformation only twice 2 once in a joint 

 which was further abnormal, since the line of demarcation separating 

 it from the preceding joint could only be followed to about the middle. 



Such an imperfect separation of neighbouring joints differs really 

 only in degree from fusion, and represents the incipi- 

 ent stage of the latter. This is proved by the fact 

 that the separation is in different cases unequal, the 

 demarcation-line protruding sometimes far into the 

 joint, but sometimes only to a slight distance from 

 the border. A complete absence of the line of demar- 



FIG. 258. Double- 

 Cation IS, Of COUrse, a fusion. joint of a Tamia, 



As usual, the slighter divergences are by far the with . tiir f e 8e3CUf ^ 



f f . J openings (nat. size). 



more common. This was alluded to in the remark 



that almost every tape-worm exhibited examples of abnormal indivi- 



dualisation. Sometimes these abnormalities occur repeatedly in the 



1 I have never found the generative openings on the surface as Heller describes and 

 figures in such segments (Art. " Darmschmarotzer,"in v. Ziemssen's, " Handh. sp. Path, 

 u. Ther."Bd. vii., p. 601, 1875; transl. "Cyclop. Pract. Med.,"vol. vii., p. 716, 1877. 



2 We have already noted (p. 419) that Tcenia vulgaris, Werner (T. dentata, Batsch), 

 is probably in reality a T. saginata which has repeatedly undergone this malformation. 



