Fig. 43. Stages in the de 

 velopnient of Dipylidim 



can iii uiii L. ( = 7 

 elliptica Batsch, T. euex 

 merino Bloeh), the cor 

 monest of the Dog- Taeniae ; 

 compare Fig. 44. 

 Six - hooked larva (no^ 

 often spoken of as 

 " Onchosphaera "); 

 larva .elongating ; form 

 tion of a central lacuna 



C, larva further advanced 



D, distinction betweei 

 body and tail is visible ; 



E, invagination of the 

 rostellum is commencing ; 



F, Cysticercoid larva with 

 four suckers, invaginated 

 rostellum, and excretory 

 vessels, c, Calcareous con- 

 cretions in cells of the 

 larva ; ex.o, excretory 

 aperture ; ex. r, excretory 

 vessels ; ini; invagination 

 commencing ; rost, rostel- 

 lum ; sc, suckers. (Alter 

 Grassi and Kovelli; highly 

 magnified.) 



vrwag 



rost 



as in most Taeniae, before it. B, Invagination commencing ; 

 above the rostellum, while beneath it the nervous system 

 invagination has now carried the suckers inwards. The tail 

 the whole larva at this stage is known as a Cysticercoid. 

 mouth of the invagination ; n, central nervous system ; rost, 

 suckers, of which only two can be seen in a longitudinal 

 present. (After Grassi and Rovelli.) 



Fig. 44. Schematic longi- 

 tudinal sections 

 through the larvae of 

 ]) ipyl id i u m ca ninum 

 L. All these stages 

 are passed in the 

 body - cavity of the 

 Dog-flea (Pulc.c terra- 

 t iceps). ( Compare Fig. 

 43 for further details. ) 

 A, Six - hooked larva 

 with developing rostel- 

 lum (shaded) and 

 suckers (black). In 

 this species the invagi- 

 nation (C, invag.) occurs 

 after the formation of 

 these organs, and not, 

 the hooks are developing 

 (dotted) is seen. C, The 

 has become distinct, and 

 hk, Larval hooks; invag, 

 rostellum and hooks ; sc, 

 section ; four are really 



