404 T. B. ROSSETER ON EXPERIMENTAL INFECTION OF DUCKS. 



the case of my Cysticercus lio])hallus, or C. quadricurvatus n. s/j., 

 that a solitary specimen is found (although as regards the former 

 the Taenia and its final host was known), that direct infes- 

 tation, by feeding, to determine the species of tapeworm of 

 which it is the larva becomes difficult, in fact out of the question, 

 because one does not care to risk — I would not — so valuable a 

 specimen as a solitary Cysticercus which I knew by comparison, 

 and the accuracy of the measurement of the hooks with those of 

 the known tapeworm, were one and the selfsame thing ; neither 

 should I feel justified in risking infestation with a single specimen 

 of a Cysticercus of an unknown tapeworm— e.g. C. quadricurvatus ; 

 whose final host might, or might not perchance, be one of the 

 Anatinidse, to produce its Taenia — until I had found another 

 specimen. 



But Stiles insists on it as a sine qua non that, until we have 

 produced the tapeworm by " direct infestation " from the 

 Cysticercus, we have no right to say, even by comparison of 

 the hooks of the Cysticercus with those of the mature tapeworm, 

 however accurately they may coincide, that this or that Cysti- 

 cercoid is the intermediate or larval stage of this or that tape- 

 worm, until we have fed with the Cysticercus, and can prove 

 that from that Cysticercus we have produced its like. This he 

 calls " direct infestation." It is logical, and no one can disagree 

 with him ; and it is this want of feeding or direct infestation of 

 ducks with Cysticercus coronula so as to produce Dicranotcenia 

 coromda, Cysticercus gracilis to produce Brepanidotcenia gracilis, 

 and Cysticercus tenuirostris to produce Drepanidotcenia tenuirostris, 

 that makes him cast a doubt and use the terms " possible" and "pro- 

 bable" on the decisions arrived at by Blanchard, Linstow, Hamann, 

 and Marazek, after careful comparison and measurement of the 

 hooks of these Cysticercoids with those of the known tapeworms, 

 that they were the Cysticercoids of these Taenia ; and to show how 

 accurate were these conclusions of my colleagues, and that this 

 Club may have the opportunity of hearing, and, I hope, placing 

 on record in its " Transactions " the " first " recorded instance of 

 the production of these three tapeworms by direct infestation with 

 their Cysticercoids or larval stage, that I have come from Canter- 

 bury this evening to exhibit my specimen of these Taenia and their 

 Cysticercoids, and to explain to you more fully the passing remark 

 I made in connection with them in my paper of last November. 



