592 DESCRIPTION OF THE ADULT T^NIA ECHINOCOCCUS. 



as T. nana,^ and, anticipating subsequent discovery, sought to refer it 

 to Echinococcus. 



It is doubtful whether the worms collected by Natterer from 

 Felis concolor belonged to the same species as our native Echinococci. 

 It is, however, certain that our domestic cats are but little adapted 

 for rearing the T. echinococcus, as I have convinced myself by repeated 

 feeding experiments. I have also experimented in vain with rabbits. 

 Although V. Siebold remarks the same in regard to the fox, which 

 also belongs to the genus Canis, the dog is not by any means the only 

 host of T. echinococcus. We know, through the observations of Panceri, 

 that it occurs in the Egyptian jackal, and Cobbold notes that it is also 

 harboured by the wolf. 



Of course T. echinococcus is not only observed in dogs which are 

 made the subjects of experiment, but occurs of itself spontaneously, 

 and in some districts not unfrequently. In Iceland Krabbe observed 

 it in 28 out of 100 dogs ; in Denmark, on the other hand,^ only twice 

 in 317, i.e., only 0'6 per cent. The conditions of life are nowhere 

 else so favourable as in Iceland, where the Echinococcus is almost of 

 common occurrence in men and cattle.'' 



That the Echinococcus of man produces in the dog's intestine 

 the very same tape-worm as does the so-called E. veterinorum, 

 follows from the proof of the specific identity of these two formerly 

 distinguished forms. Nevertheless, the first feeding experiments (of 

 Kuchenmeister, Zenker, and Levison) yielded at first only a negative 

 result. The reason of this lay perhaps in the nature of the material 

 used, which, when obtained from the human corpse, is seldom so fresh 

 and well preserved as that from the ox, and partly also in the indi- 

 vidual conditions of the animals experimented on. For it does not 

 always happen, as v. Siebold has shown, that they are suited for the 

 rearing of the Tcenia from the Echinococcus. Later investigators have 

 been more fortunate. Thus Naunyn gave to two dogs the contents of 

 an Echinococcus from the liver, procured by tapping. One of them 

 exhibited, after thirty-five days, numerous Tcenice, 3-5 mm. long, and 

 with eggs in their terminal joints. The other dog was examined eight 



^ "M^m. sur les vers intestin.," p. 158 : Paris, 1858. Kuchenmeister ("Parasiten," 

 second edition, p. 162, note) severely reproaches "the zoologist" v. Siebold, because in 

 1853 he did not know that T. echinococcus had been in 1850 described by " the zoologist " 

 van Beneden as T. nana; but the reproach is as unjust as it is frivolous, since van 

 Beneden's memoir, presented in 1852 to the Paris Academy, vras only published in 1858. 



' Similarly, in Giessen I only observed Echinococcus in the subjects of my experiments, 

 while from Gottingen the intestines of dogs infected with them were several times sent 

 to me. 



' [Thus it appeared formerly. I have recently learnt from Thomas (" Hydatid Dis- 

 ease," p. 191 : Adelaide, 1884) that in South Australia no less than 40 per cent. " of the 

 unregistered dogs " are infected by Tania echinococcus. — R. L.] 



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