136 ANIMAL PARASITES. 



in the neck. I did not detect any anastomoses between the 

 individual branches of the sucking discs. The longitudinal branches 

 constantly become thicker as the segments increase in size, and, 

 when cut through, show a distinct lumen, each two lying close 

 together. I could not detect the anastomosing tran verse branch 

 on the posterior margin of each segment, which should always 

 occur in the Teenies. On the other hand, at these points I found 

 small enlargements of the vessels, distinguished by a kind of 

 valvular apparatus, which appeared to open before the fluid 

 streaming from the head, but closed itself against that running 

 back towards the head. When an air-bubble accidentally occurs 

 in these swellings, the action of this vascular cone may often be 

 easily recognised by a little pressure, especially in spirit-spe- 

 cimens softened again in caustic potash. When the segments 

 are held against the light, these dilatations are particularly well 

 shown, projecting half into the upper, and half into the lower 

 segment. Hence we can only hope to make successful injections 

 by operating from the head backwards. 



The segments, which have a great tendency to increase in 

 breadth, are at first 1 millim. in length, and about 3 in breadth. 

 Afterwards, also, the breadth predominates over the length for a 

 long time, for the segments are 10, 14, 15, 17 millim. broad, by 

 9 14 millim. long. But this proportion does not remain con- 

 stant, and segments of 1 l|in. in length, and only 3 4 lines 

 in breadth are met with. By this means the first half of the 

 segments acquire the appearance of segments of Bothriocephalus, 

 with lateral genital pores. The change of form is explained by 

 the circumstance that only the longitudinal muscles reach from 

 the upper to the lower margin of the segments, whilst the trans- 

 verse muscles cease at a greater or less distance from the margins. 

 That the last segments, or proglottides, have a tendency to pass 

 away without faeces, is beyond a doubt, but this also takes place 

 with T. solium, although more rarely. The segments pass when 

 the patient is standing quietly, and, falling into the trowsers, he 

 suddenly has a moist and cool feeling about the legs, and when 

 he seeks to free himself from this unpleasant sensation, he finds 

 a single proglottis attached to or creeping about his leg. When 

 this T&nia is expelled, it breaks off with remarkable ease close to 

 the neck, and then the first segments form series of joints, which 

 hang one after the other like the pearls of a necklace upon a 

 thread. These are the segments erroneously regarded by Seeger- 



