The nervous system in the Cestode Moniezia expansa. 367 



platinic chloride (in 5 ccm dist. HgO) . 5 g 



osmic acid crystals 2 g 



After having remained in this mixture for ten hours the worms were 

 removed and cut into pieces from 1 to 3 cm in length. These 

 were put first into crude pyroligneous acid for from 6 to 10 hours, 

 and then into 70°/o alcohol for 24 hours. After being dehydrated and 

 inbedded in paraffine they were cut into sections 6^/3 jt< thick. This 

 method gave preparations in which the nerves were colored grayish 

 blue, the more highly refractive muscles brown , and the connective 

 tissue pale gray or steel blue. 



II. Description of the Nervous System. 



A fresh adult specimen of Moniezia expansa is commonly about 

 1 m in length , and from 10 to 15 mm broad at the posterior end. 

 In such an animal there are between 500 and 1000 proglottides. The 

 scolex is on an average 1 mm in diameter and 2 mm in length, 

 measured from the anterior end to a point just posterior to the 

 cephalic ganglion; but the dimensions of the scolex vary considerably 

 in different animals. There are neither rostrum nor hooks in this formf 

 There are two sets of sexual organs in each proglottis, opening one 

 on either margin of the proglottis in a gonopore. The musculature is 

 well developed and is similar to that found in other Taenias. 



The anterior part of the excretory system in the scolex of Mo- 

 niezia expansa consists of a horseshoe-shaped tube the curved end of 

 which is situated at about the level of the anterior nerve ring. It 

 lies in the frontal plane and is divided symmetrically by the sagittal 

 plane. Each of the arms of this tube fork, giving rise to branches 

 that pass respectively dorsal and ventral of the cephalic ganglia 

 (PI. 21, Fig. 1). These branches have been designated as the dextro- 

 dorsal, va. dx-d; the dextro- ventral, va.dx-v; the sinistro-dorsal, va.s-d, 

 and the sinistro-ventral longitudinal excretory tubes (PI. 21, Figs. 1, 

 5 and 6). These four tubes bend slightly outward (PI. 21, Fig. 1), 

 passing close to the surface of the cephalic ganglia, opposite which 

 they turn sharply outward and forward; but, after continuing for a 

 short distance in this direction, they turn backward through an angle 

 of more than 90 ^ and run parallel to one another and to the lateral 

 nerve. These four excretory tubes pass backward through the neck 

 region into the younger proglottides, the dorsal pair becoming larger 

 and occupying the position of the longitudinal excretory tubes of the 



