EXAMINATION OF HELMINTHES 



151 



smaller strands placed dorsally and ventrally of the main cord. They 

 appear as finely dotted discs. In Dibothriocephalus, these nerves lie 

 closer to the middle line, well within the middle layer ; while the 

 excretory vessels, the net-like formation of which has already been 

 described, appear as variously-shaped gaps in the parenchyma of the 

 cortical layer. Sections of Dibothriocephalus differ, moreover, from 

 those of the Taenia varieties in the arrangement of the reproductive 

 organs. These will be readily identified, however, if their arrangement 

 has been previously studied in whole specimens. 



Exg. 



Cu. 



Lm. 



Lm. 



Scz. 





l*_ Tnn. 



N. 





Smn. 



FIG. 71. Half of a transverse section from a mature proglottide of Tania crassicollis. 

 Cu., Cuticle. Exg., External excretory vessel (to the right of it is the internal excretory 

 vessel). .ff.,Testes. Lm., Longitudinal muscles. N. t Nerve- cord with accompanying 

 strands. Scz., Subcuticular cells. Smn., Sub-median nerve-cord. Trm., Transverse 

 muscles. Ut., Uterus. 44:1. 



Lm. Cu. 



D. 



Lm. 



H. N. D. 



FIG. 72. Half of a transverse section from a proglottide of Dibothriocephalus latus, 



taken at the level of the cirrhus-pouch, C. Cu., Cuticle. D., Yolk-gland follicles. 

 H.,Testes. Lm., Longitudinal muscles. N., Nerve-cord. Sc. , Subcuticular layer. Tm., 

 Transverse muscles. Ut., Uterus. 30:1. 



The beginner should not fail to make sections of the head in order 

 to make himself familiar with the structure of the suckers and, in 

 the case of the Tseniidee, of the rostellum. Sections of the rostellum 

 should be taken transversely. The study of the nervous system of 



