ZOOLOGY. 21 



" Although the ' proglottiilcs ' arc only produced in the alimentary canal of man, 

 or some other warm-ljloodcd animal, it is necessary for the evolution of an embryo, 

 that the ovum should be swallowed by some other animal than the one inhabited by 

 the mature worm. When the fecundated ' proglottides ' therefore arc exi)elled, the 

 ova are liberated, and should an ovum get into the alimentary eaual of a vetehrato, 

 the embryo (now called a ' pi-oscolex '), set free from its covering, proceeds to boro 

 ■with its spines through the tissues of its ' host ' until it finds a resting-place, then 

 it surrounds itself with a cyst, and a vesicle containing a fluid is developed ; it is 

 now called a ' scolex.' These cysts were also known as ' hydatids.'' 



" When ova of the pork tape-worm {Tccnia solium) gains access to the alimentary 

 canal of a pig, their shells become digested, and the inclosed six-hooked embryos 

 escape, and boro their- way into the circulation. Thence they proceed to the cellular 

 tissue and become transformed into 'measles' (Ci/sticercus cellulosa). In the sheep 

 the cystic worm of the brain [Cccnurus cerebndis), which causes the ' gid ' or 

 'staggers,' becomes Wv Tcenia cammis of the dog. The Cysticcrcus pisiformis, or 

 ' pea-measle ' of the rabbit, is the ' scolex ' of I'atiia serrata infesting the dog. The 

 Cyxticercus fasciolaris of the mouse becomes the Tcenia crass icollis of the cat. The 

 common hydatid {Echinococcus rdcrimrnm) becomes the Tania echinococcus of the 

 dog. The slendei'-neckod hydatid ( Cysticcrcus tenuicollis) of the sheep becomes 

 the Tania maryiiuilu of the dog. The Cysticcrcus talpie and C. ImigicoUis infesting 

 moles become respectively the Tcenia tenuicollis and T. crnssiceps of the fox. Lastly 

 a 'scolex' called Staphylocystis micracanthus, which is found in a myiiapod [Olomeris), 

 is the larval stage of Tania pistillum infesting shrews {Sorex)." (C'obbold, quoted by 

 Pascoe, op. cit. p. 53.) 



The risk a man runs of eating the ' scolex ' of a taenia in a piece of pork or beef, 

 and thereby introducing a tapeworm into his alimentary canal, is far less than that 

 which arises from swallowing its ' ovum.' This latter is hatched in his stomach, 

 whence it bores its way into his tissnos, as it would into those of a pig, causing the 

 man to bo ' measly,' rice the pig. Van Bencden describes one possible and highly 

 painful result: " We have lately read an account of the effects produced by one of 

 these wandering worms on a man 'odio died after suffering from a peculiar disturbance 

 of the mind. Two spirits seemed to haunt and speak to him, the one a German, the 

 other a Pole. Filthy images were called up before his imagination. At the post- 

 mortem examination ' cysticerci ' were found to occupy the ' sella turcica ' near the 

 commissure of the optic nerves. One of these was alive, the others were calcified. 

 Two others in a similar condition occupied a lobe of the brain." What a lesson 

 of caution and forbearance in our judgment of our afflicted brethren does not this 

 teach us. Doubtless many who knew this poor man put down his sufferings as the 

 result of an immoral and wicked frame of mind, while all the time the poor ■wretch 

 ■was helplessly suffering fi-om a wandering ' scolex,' which had established itself in his 

 cerebellum. Immoral ideas are often the tlirect result of injury to or disease of the 

 cerebellum, and who shall say in such sad cases that a wandeiing ' scolex ' imbedded 

 in that organ is not the truly responsible cause ? 



In the tape-worm {Tania) each new joint is formed between the head and the 

 next joint, so that the maturity of the joints bears some proportion to their distance 

 from the head. The dislodgemcnt and expulsion of these creatures from their 

 intestinal a])ode is extremely difficult, and the best mode of guarding against their 

 invasion is to eat no raw or underdone meat, as thorough cooking is destructive to 

 the 'scolex,' but no meat is safe in this respect which when cut displays a san- 

 guineous hue in its juices. The ' Cysticercus' of beef, it may be ad<lc<l, produces 

 the Tania medio-canallata in man. Of the ' gid ' in sheep a few remarks by Van 

 Beneden are worth quoting. A sheep in pasturing swallows an egg of the Tania 

 cmnurus di'oppcd by some passing dog. The 'scolex' finds its way to the brain, and 

 in fifteen days the first symptoms of ' gid ' appear. The sheep necessarily dies at 

 last, unless the parasite is removed by the ' trepan.' To arrest the spread of the 

 disease only one thing is necessary, to destroy by fire the head of every sheep 

 attacked by the 'gid,' so as to prevent its ' cysiicercus' passing into the .stomach of 

 any carnivorous animal ; as the mischief may be indefinitely propagated by such 



