518 GROWTH AND DEVELOPMENT OF T^NIA SOLIUM. 



worm 90 cm. long, with proglottides just mature, was expelled exactly 

 four weeks after an unsuccessful attempt at expulsion, which left only 

 the head remaining. 1 



As to the age to which the worm may attain, we have here no 

 greater certainty than in the case of Tcenia saginata. This much, 

 however, is beyond doubt, that the hook-bearing tape-worm may per- 

 sist for a long series of years perhaps for fifteen or twenty, or even 

 /or several decennia but for how long is uncertain. In all these 

 cases, there is always the possibility that the old inmate has been 

 unconsciously replaced by a successor. 



As a rule the parasitism of the worm ends by its expulsion from 

 the host in toto. Whether dead or living, it is quite the same for the 

 host, the expulsion takes place when the worm is no longer able to 

 resist the pressure of the chyle or of the intestinal muscles. We have 

 already noted in connection with Tcenia saginata that the worm may 

 under certain circumstances remain in the intestine for a while after 

 death, until it falls to pieces or becomes mummified. The worm- 

 mummy there described (Fig. 273) could be referred with some cer- 

 tainty to T. solium. 



Malformations. 



Malformations, properly so-called, are much less frequent in the 

 hook-bearing tape-worm (the case is different with the bladder-worm) 

 than the hookless Tcenia saginata. I have only seen one instance. 

 This was a proglottis with two symmetrical sexual openings and 

 genital ducts an abnormality which we have already noticed in T. 

 saginata (p. 471). 



On the other hand, here and there, six-rayed individuals occur. 

 Krause 2 mentions a Cysticcrcus cellulosce with six suckers, found in the 

 brain of an idiot, and Zenker found on dissection of a tuberculous 

 patient fourteen immature specimens of Tcenia solium, one with six 

 suckers and twenty-eight hooks. The adherent worm, which measured 

 46 cm., corresponded in respect of the prismatic form of its proglottides, 

 and the position of the genital openings on the median ridge, with 

 the analogous malformations of T. saginata* 



1 This worm showed in lengths of 25 cm. 350, 128, and 69 joints, and including the 

 last 33 joints, which occupied 15 cm., had in all 580 joints. The largest joints measured 

 5 mm. long by 4 '8 mm. broad, and were almost square, but still without embryos. The 

 gradual growth of these joints may be expressed by the ratios 1*8 : 2*5 : 3 "4 in width, to 

 2 : 3'6 : 4 in length, these being the dimensions in millimetres, both measured at the ends 

 of the first three portions of 25 cm. 



2 Gottingen Nachrichten, No. 18, 1863. 



3 Heller, loc. cit., p. 594 (Eng. transl., voL vii., 709). 



