CONNECTION BETWEEN TAPE AND BLADDER WORMS. 333 



worm heads which the latter possess form an appendage, but on this 

 strange soil this gets changed by " dropsy " into a bladder. 



Von Siebold gave his theories special point and weight by taking 

 a special case of resemblance, instead of merely dilating on the general 

 similarity ; he emphasised the likeness between the head of the cystic 

 worm infesting the mouse (Cysticercus fasciolaris) and the tape-worm 

 of the cat (Tcenia crassicollis), a comparison which had been previously 

 expressly made by Pallas and Goze. ' " Some individuals of the brood 

 of Tcenia crassicollis" he says, " go astray in the rodents, and degene- 

 rate into Cysticercus fasciolaris; but when their hosts are eaten by 

 cats, and the worms are thus transplanted to their fit soil, they cast 

 off their degenerate joints, and, returning to the normal form of Tcenia 

 crassicollis, become sexually mature." 



To this theory v. Siebold clung all the more firmly when he found 

 Ktichenmeister's results confirmed by his own experiments. 



In the changes undergone by the bladder-worm after their trans- 

 mission into the intestinal canal, ^ he recognised no normal meta- 

 morphosis, but only the remedying of a previous abnormality. When 

 the bladder-worms had altered their form in their new environment 

 he called them "healthy," and thought that there were only certain 

 forms which could pass through such fates to the tape-worm stage. 



I must confess that I shared v. Siebold's theory for a while.'' I 

 was unfortunately as little aware as v. Siebold of the beautiful ob- 

 servations which Goze had made on the development of the cystic 

 worms, and especially of that form found in the mouse, which was the 

 more unfortunate since these observations were in reality decisive on 

 the point in question, and gave a direct proof, not of the pre-existence 

 of the head, but of the bladder. " The first thing," said Goze,* "to 



' See Pallas, "Miscell. Zoolog.," p. 170, and Neue nordiscJie Beitrdge, Bd. i., p. 82 ; 

 Goze, loc. cit., pp. 222, SOi. The latter speaks as follows: — "In size, shape, and 

 structure, the head of the Tcenia serrata fdina ( = T. crassicollis) is wholly identical with 

 the head of the jointed bladder tape-worm from the liver of the mouse, for the latter also 

 has no neck, but has its head directly contiguous with the first joint. But why these two 

 forms are so similar in the structure of their head, and yet so different in other respects — 

 who can tell ? " 



^ Zeitackr.f. wiss.'Zool., Bd. iv., p. 407, 1852. 



° " Beobachtungen und Keflexionen iiber die Naturgeschichte der Blasenwtirmer, " 

 Archivf. Naturgesch., Jahrg. xiv., Bd. i., p. 7, 1848. According to Kiichenmeister (" Para- 

 siten," 2ded., p. 19), I held, even in 1857, that the grouping of the Oystici along with the 

 tape- worms was entirely unwarrantable; nay, "I then had no idea of the systematic 

 relation of the two forms." These assertions, dogmatic as they sound, only show that 

 EUchenmeister's literary-historical studies are not less superficial than his anatomical and 

 embryological ones. I am in no way responsible for van dtr Hoeven's " Handbook of 

 Zoology," nor for the translation of the first volume which appeared in 1851, on which 

 Kiichenmeister has relied for the truth of his statements. 



* " Versuch einer Naturgeschichte der Eingeweidewiirmer," p. 245, 1782. 



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