FURTHER DEVELOPMENT OF THE BLADDER-WORM. 575 



exhibited stellate or linear scars, just like those found in the liver of 

 the rabbit after the exit of Cysticercus pisiformis. Besides this, the 

 connective tissue capsules of the mesentery were, on their internal 

 surface, without that granular exuded layer which was usually found 

 in the first breeding-place of the worm. Instead of it there was a 

 layer of slightly granular, clear, and pale balls, which in many re- 

 spects recalled pus corpuscles, and were about double the size of 

 blood-corpuscles. 



I need hardly describe in detail the structure of the head pro- 

 cess. It consisted of an opaque mass of nearly spherical form, and 

 24 mm. in diameter, which was in marked contrast to the semi- 

 transparent bladder, and occupied the whole of the anteriorly pro- 

 jecting wart-like summit of the latter. The circlet of hooks, the 

 rostellum, and the suckers were fully developed. The body, closely 

 connected with the head, had a length of almost 4 mm., and a some- 

 what large transverse section. In histological respects, also, the head 

 had completed its development, as was sufficiently shown by the 

 distinct muscular fibres, calcareous corpuscles, and vessels. 



I found bladder-worms in essentially the same condition in a 

 lamb three months after feeding. The only modifications worth 

 mentioning w r ere in the size of the bladder, which, with a breadth 

 of about 12 mm., had now grown to double the length, while in a 

 fresh condition its vessels could be plainly distinguished even by the 

 naked eye. Especially noticeable, as in Cysticercus cellulosce (p. 509), 

 were two irregularly branched longitudinal stems, which ran down 

 from the head-process towards the posterior end of the body, and 

 broke up into an extremely delicate net- 

 work. The external surface of the bladder 

 was traversed by fine longitudinal and 

 transverse wrinkles, which (perhaps in 

 consequence of the contraction of the 

 muscular fibres lying under them) were 

 closely crowded together. The head-pro- 

 cess and receptacle had exactly the pre- 

 vious structure. The former, in its 

 original invaginated state, with its bend- *>. j* 11 - A * Cysticercus tenui- 



j , . . colhs, three months old (nat. size) ; 



ings and tolds, filled up the interior of the B, The head-process (xio); a, 

 latter. It required a somewhat powerful rudiment of the ribbon-like process, 

 pressure to expel it, whereupon it of course turned its formerly interior 

 surface outwards, and assumed the attitude of the subsequent tape- 

 worm body. In this state the length amounted to between 5 and 6 

 mm., and its breadth at the lower end to fully 2 mm. 



From the analogy between these bladder-worms and the related 



