100 ON ANIMAL PAKASITES. 



tape-worm exhibits a series of extraordinary transformations. In 

 order to produce an embryo, the ripe joints must first escape from 

 the bowel of the warm-blooded animal in which it was produced 

 and the ovum swallowed by some animal of a lower type. In the 

 Tccnia solium, one of the tape-worms of man, for example, when 

 a joint or ripe " proglottis " escapes from the bowel, the ova are 

 liberated by the decomposition of the " proglottis," and it is easy 

 to understand how one or more of them may be swallowed by a 

 pig. When this happens, a " proscolex " is liberated from the 

 ,9yiifli, and it bores its way through the walls of the stomach, and 

 .■,eV<?ysts itself in the muscles, when it becomes a " scolex," or 

 ;Gy^tiG worm [Cysticercus ccllulosm), producing what is called 

 Y'liieasl^ " in the pig. Wlien thus encysted in the tissues of the 

 animalj the " scolex " consists simply of a tsenioid head, united by 

 j%.Gqntracted neck to a vesicular body. It remains encysted for 

 ^JWQ indefinite period, until perhaps a piece of the " measly pork " 

 %Hea,ten by a jnan, when it at once fixes itself to the coat of the 

 intestine, dev-elofps into a tape-worm, and begins to throw off 

 ;t"-, proglottides," becoming thus the "strobila" of the Tcenia 

 soli%f))i witl^ which we started. There are, however, a great 

 variety (pf tape- worms, all inhabiting different animals. There 

 are at least two common to man, the Tmnia solium, just men- 

 tioned, as derived from the " measles " of the pig, or the cystic 

 embryo form of the worm known as Cysticercus celhdoscc ; and 

 the Twnia mccliocancettata, derived in like manner from the measles 

 ■'Orf the ox, but which is, happily, far less common. Similarly the 

 tape-worm of the dog, Tmnia cc&nurus, is the mature form of the 

 •%ystfe Worm of the sheep; Cosnurus cerebrcdis, and which causes 

 ^the disease in sheep known under the various names of " sturdy," 

 '■"-gid," and " staggers." Several other tape-worms infest the dog ; 

 -6ne, Tccnia serrata; is. common to both the dog and the fox, and 

 ■is derived from the cystic worm found in the livers of hares and 

 rabbits (Cysticercus pisiformis). The tape-worm of the cat 

 (Tccnia crassicollis) is derived from the cystic worm found in the 

 livers of T^ttsund' mitie (pysticei-cus fasciolaris). A sheep affected 

 with "sturdy" may -often be- successfully treated by trepanning, 

 but, as a rule, although the life of the animal is saved, it is never 

 #orth much- afterwards. The operation must be performed as 

 ^'soon as ever the ■skull softens over the spot where the cystic 

 •embryo li'^s, and while there is but one bladder iattlie brain. 

 This is ttene by piercing the brain, and drawing -©ff tihe liquid 

 •from within the cyst of the pameige throuMl a 6an^la, by means 

 ^f fe syringe^ and then jdrawifig out the bla'dkfei?'ifcit is^^^ossilsle. 

 f'^i^MiikeS-pT'^epar'M ^^(9rms'^(Ti'etiiatoda).-**Some ofc these w^rms 

 ^#e^|)a¥a^itic tipori-thte iexterior, and otliei'S-njpoin 'the liver aijd 

 ^iMtlernal organs '^f'sheepy^^bir^, 'and fish©^^^ &Ci' .'Th^y? are flat, or 

 4*^her oval in- eh^pCj and- never more than an inch or two in 



