574 T^NIA MAEGINATA AND CYSTICERCUS TENUICOLLIS. 



the position of the head-process and in the late period of its formation. 

 The straight position of the head lasts, however, only for a short time. 

 After the head is fully developed and its pedicel begins to grow, the 

 head-process in Cysticercus tenuicollis (Fig. 311) folds together in the 

 interior of the receptacle, just as in the majority of the other bladder- 

 worms. 



Before proceeding, however, to the consideration of the other 

 changes undergone by the worms, I may mention that recently 

 Baillet in Toulouse has, by experimental investigations on Tcenia 

 nmrginata, obtained results which are strictly in accordance with the 

 preceding ones. Of these experiments, 1 shall only make special 

 mention of one which was made on a lamb. The latter received at 

 three different times, between the 4th and 10th of April, one, five, and 

 eleven proglottides of Tcenia marginata {T. Cysticerci tenuicollis, 

 Baillet). It became very ill on the fourteenth day after the feeding, 

 and died towards evening. On dissection there was found in the 

 abdominal cavity a considerable ecchymosis, which originated from 

 the numerous small streaks penetrating the congested liver. Each of 

 these streaks consisted of a tube, whose wall (unquestionably an 

 exuded layer) was easily distinguished from the parenchyma of the 

 liver, and whose blood-filled interior contained from one to four small 

 oval bladders. These measured from 0'6 to 3"5 mm. (or, in the smaller 

 diameter, 0'35 to 2 mm), and, in spite of the absence of a head-pro- 

 cess, were with all justice regarded as young bladder-worms. Some 

 of these streaks had opened externally, and had poured their contents 

 of blood and bladders into the body-cavity. Some young Cystkerci 

 were also found in the lungs and omentum ; in the former situation 

 generally in the centre of a more or less extensive ecchymosis. The 

 whole number was estimated at several thousands. 



Thus it will be seen that the result of this investigation fills up, 

 in a very welcome manner, the gap between Leisering's experiments 

 and my own ; and as Baillet himself clearly states, gives fresh support 

 to the hypothesis of a wandering occurring through the blood-vessels. 

 Baillet's other experiments yielded much less striking results, and 

 also produced a much smaller number of bladder- worms (19, 1, 8, and 

 30), although the number of proglottides administered was not less 

 than in the first case. 



As to the changes undergone by the worm after the transference 

 into the cavity of the body, I first succeeded in observing them in a 

 young pig, infected seven weeks previously, in which the bladder- 

 worms were about the size of a filbert (15 mm.), and were already encap- 

 suled in the omentum ; but that in this case also the original abode of 

 the worms had been the liver, was shown by the fact that its surface 

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