358 ANNUAL OF SCIENTIFIC DISCOVERY. 



vi/. little worms with long tails, the so-called Cercarians, which originate 

 in the body of the yellow worm by a kind of budding. In the third genera- 

 tion, these Cerearians are brought forth by the mother, swim for a while 

 free in the water, and then become a kind of pupa, forming a cyst around 

 themselves, and in this state seeming to wait till, by chance, they are swal- 

 lowed by a vertebrated animal, in which they become in a few days, as is 

 shown by experiment, a perfect Distoma. 



Dr. Weinland has found a new species of Cercaria, the first known in this 

 country, in the liver of the Pliysa Jieterostropha, and he concludes, from fur- 

 ther investigations, that this Cercaria belongs as a larva to a blackish-spotted 

 Distoma, which he has found frequently in the lungs of frogs and toads, and 

 once in the intestine of a turtle, and which he proposes to describe under 

 the name of Distoma atriventre. 



He added that a similar alternation of generation takes place in another 

 order of Helminthes or parasitic worms, viz. the order of Cestoda. The 

 investigations of Kuchenmeister and Siebold have shown that the cysts 

 in the flesh of the hog, causing the condition known under the name of 

 " measly pork," are pupae of the human tapeworm, and that they develop 

 themselves into the latter when taken into the human intestine; and that 

 the human tapeworm, when eaten by a hog, produces in this animal these 

 cysts. In three instances, in which he had seen tapeworms in Americans, 

 these worms were identical with the TtEnia solium, the tapeworm of the 

 English and Germans, the same species upon which the experiments of 

 Kuchenmeister were made, not the Bolriocephalus latus, the tapeworm of 

 the French and Swiss, which seems to have a different kind of development. 

 He had found a larva of a tapeworm, a so-called Scolen, with two large red 

 spots behind the head, in the intestine of the common alewife (Alosa Ameri- 

 cana), provided with four large suckers (acetabitla), but not having an articu- 

 lated body, nor genital organs. This larva was destined, as he supposed, to 

 become a perfect tapeworm only in the body of another vertebrated animal 

 by which the alewife might be swallowed, perhaps in a shark. He had 

 found another larva of a tapeworm, the TetrarJiynchns Morrhuce, Rud. ( T. 

 corollatus, Siebold), in a cyst near the heart of the common codfish. He 

 had found the larva of tapeworms, known under the name of Cysticercus, 

 in the pelvic region of the American hare (Lepus Amcricanus), and in the 

 liver of the rat (Mus decumanus). After a careful comparison he found 

 them identical, one with the Cysticercus of the European hare, and the other 

 with that of the European rat; which become, according to the experiments 

 of the same helminthologist, Kuchenmeister, the first, the tapeworm of the 

 dog, and the second that of the cat ; a fact likewise noticed by the American 

 hunters. 



Dr. Weinland supposed that this Cysticercus of the American hare came 

 from the European dog; the eggs of the tapeworm having been swallowed 

 by the hare, perhaps with vegetable food. In another and new species of 

 tapeworm, the T(emapnnctata,Wem\., found in the gold-winged woodpecker, 

 he had observed the embiyo just hatching. The shell of the egg of this 

 worm has two processes, each terminating in a large ball; the embryo is 

 provided with six spines. Some years ago, Dr. Hein and Dr. Meissner found 

 pupre of tapeworms in cysts in a land-snail (Ildix pomatia), and in a beetle 

 ( Tenebrio molitor), and in the cyst were found six little spines thrown off by 

 the embryo. Thus we have reason to believe that that hatching embryo, 

 with its six spines, penetrates into an insect or a mollusc, forms there a 



