FORMATION AND DEVELOPMENT OF THE RUDIMENTARY HEAD. 503 



layer of fibres, which pass from the head into the musculature of 

 the bladder, and which must have been previously present in a 

 less developed state, but also cells of another nature lying next the 

 cuticle, which have a different appearance, inasmuch as they assume 

 a spindle form, and impart to the deeper layer a very striking 

 radiate character. 



We need hardly expressly mention that the outer muscular layer 

 of the head-rudiment represents that structure which we formerly 

 designated the "receptacle," and which we saw to be of general 

 occurrence in the larger cystic tape-worms (p. 346). 



This receptacle lies at first close upon the outer surface of the 

 head-papilla. For a while the two structures grow with perfect 

 uniformity, but soon one sees, in bladder-worms about 2*5 mm. long, 

 that the head-papilla obviously, in consequence of its greater longi- 

 tudinal growth, curves round in a bow inside the receptacle, and 

 assumes a bent position (Fig. 280). As long as the curve is not very 

 marked, the club-shaped end of the head lies still, almost perpen- 

 dicularly under the point of attachment, but afterwards it bends more 

 and more to one side, until the angle finally (Fig. 281) comes to lie 

 at the deepest point of the receptacle. The latter thereby loses its 

 former regular shape ; the lateral surface which lies next the end of 

 the head is protruded like a hernia ; thence it bridges over the angle 

 between the two portions of the bent head, and passes towards the 

 point of insertion. 



FIG. 280. The beginning 

 of the bending of the head 

 of Cysticercus celluloses 

 inside its receptacle. ( x 25.) 



FIG. 281. The head and re- 

 ceptacle of a bladder-worm from 

 a muscle about 6 mm. in size. 

 (x25.) 



In this state the head-rudiment persists until the long diameter 

 of the bladder-worm has increased to about 6 mm., 1 when it 



1 Since these early stages of Cysticercus celluloses have not been before observed in 

 man, I may note that similar forms were once (1860) sent to me for examination and 

 identification by my colleague Professor Wagner of Leipsic. They originated from the li ver 

 in a case of tuberculosis, were about one line in size, and occurred in considerable numbers, 

 about one for every square inch. 



