514 GROWTH AND DEVELOPMENT OF T^ENIA SOLIUM. 



The difference in this case is probably to be explained by the fact 

 that the animal used does not afford the proper habitat, which, indeed, 

 is found only in man. 



The youngest tape- worms as yet observed in man are those which 

 Kiichenmeister found in the criminal fed by him seventy-two and 

 sixty hours respectively before death. These specimens measured 

 from 3 to 4 mm. in length (with the exception of one only which was 

 twice as large), and showed on the posterior end of the body, where 

 the bladder had been attached, a small notch-like constriction, as is 

 seen in all tape-worms immediately after their separation from the 

 bladder (p. 382). Nothing is said about segmentation, but we can 

 well believe that it was present, at least in the larger specimens. 1 



Had the nature of the end of the body been different, we might 

 have taken the young worms for Tcenice, which, by the loss of their 

 joints, had been reduced to head and neck, and were now commencing 

 the formation of a new chain of joints. The changes undergone by 

 the young tape-worm are exactly like those exhibited by a surviving 

 head. The posterior appendage lengthens, and separates into a series 

 of joints, which become posteriorly more and more marked, as they 

 become separated by the intercalation of new segments ever further from 

 their point of origin. At the same time they are rapidly growing in 

 size and development, so that from an inconspicuous head a very con- 

 siderable chain soon results. 



Although Tcenia solium is decidedly behind T. saginata in its size 

 and in the number of its joints, it is still one of the most conspicuous 

 cystic tape- worms, for it exceeds the other species of this group by at 

 least a metre. This predominance is not determined by the proglot- 

 tides remaining longer united, but, as in T. saginata, by a luxurious 

 vegetative growth and formation of joints, which proceed so quickly, 

 indeed, that the individual development is to a certain extent out- 

 stripped. As in the hookless tape-worm of man, the joints attain 

 their final size and development only at a considerable distance from 

 the head. 



But the form of the tape-worm and the growth of the joints are 

 perhaps best expressed by measurements. I shall first refer to an 

 animal about 224 cm. (that is, about 9 feet long), which was found 



1 Heller reports, in the case mentioned on page 497, that he found " no joints visible 

 to the naked eye " on the " very small " tape-worms, even eighteen days after the trans- 

 mission of Cysticercus cdluloscc. This does not, however, prove the real absence of seg- 

 mentation, for we may compare it with his other statement that the segmentation in the 

 adult Tcenia solium begins 3 cm. behind the head. The first joints are so small that they 

 are hardly ever recognisable by the naked eye. The remark that the worms were all 

 very small, leads one also to conjecture that the conditions of development the experiment 

 was made on a consumptive patient were but slightly favourable. 



