250 Transactions of the 



hence it may conveniently, if not systematically correct, be desig- 

 nated Cijsticercus ovipariens, habitat sheep. 



Doubtless sufficient will have been said to awaken the curiosity 

 and stimulate to further research, on the part of those who may be 

 more fortunate than myself, to procure an entire or undamaged 

 specimen from one of our ordinary herbivora. 



For the benefit of those who may be unacquainted with the 

 curious phases of these migrating parasites, I venture to briefly run 

 over some of the important points, and in so doing shall borrow 

 largely from Dr. Cobbold's very valuable and learned treatise on 

 Entozoa, at the same time noticing his opinions, which must have 

 great weight from his large experience, yet which are contrary to 

 the facts above mentioned, — the exception, so to say, proving the 

 rule. 



The ordinary tapeworm condition, Van Beneden termed the 

 strobila, the joints of which are called proglottides ; these sexually 

 mature joints may retain an independent life, and the ova developed 

 in them furnish each the proscolices of Van Beneden — a 6-hooked 

 embryo. According to his view these become the nurses, or 

 scolices, and are represented by the well-known hydatid, or 

 cysticercus. These Cestodes are stated to be bisexual, have alternate 

 generations, and migrate to various hosts for the purpose of 

 preservation of their kind. Dr. Cobbold says the tapeworms are 

 characterized by the possession of a small distinct head, furnished 

 with four simple oval suckers and commonly with a more or less 

 strongly pronounced proboscis placed at the summit of the median 

 line ; this is retractile, frequently furnished with double or a single 

 row of chitinous or horny hooks and booklets ; sometimes the rows 

 are greatly augmented, and aid to determine the species. The 

 joints are bisexual. In one of the six species of tapeworms of the 

 dog, which he selects for example, the Tsttnia serrata, the double 

 row of hooks amounts to 48, 24 in each row. In experiments made 

 by administering its separate joints or proglottides to a rabbit, 

 Leuckart found after 24 hours in parts of the venous system, the 

 minute 6-hooked embryos, which had been developed from the ova 

 in the joints, and on the fourth day small cysts in the liver, each con- 

 taining a minute embryo of shs of an inch in length. These grow 

 rapidly, and two days later reach the length of ^ of an inch, and 

 after eight or nine days the spots are visible on the liver. Later 

 on, these increase, becoming longer and narrower at one end than 

 the other. The organ attacked sets up a sort of self-defence, as 

 a protection against the presence of the parasite, and produces 

 a closed cavity of connective tissue. The embryos themselves, by 

 differentiation, further obtain structural characters, as epidermis, 

 Muscular fibre, &c, and make use of their boring propensities, 

 he anterior end of the embryo becomes turbid in appearance, 



