116 



Tlie genital openings are not prominent, and are very slightly 

 developed, as compared with those of other Anoplocephalids. The genital 

 openings are irregularly alternate. 



Anatomy. 

 The Cuticula. — 



The cuticula on scolex and strobila everywhere presents a similar 

 appearance, and is composed of three distinct layers, differing from each 

 other in thickness, structure and in their behaviour towards staining 

 reagents. 



For the study of the cuticula, specimens fixed with silver-nitrate and 

 developed with hydroquinone give on the whole the best results. (Method ; 

 Ramony Cajal for nervous tissue.) 



In a specimen fixed in this manner and stained with haematoxylin 

 counterstained with orange g, the cuticula at 15 cm. from the scolex is 

 about 4-5 f- thick; of this the outer layer accounts for about 1-5 i«, the 

 middle for 3 f*, the innermost layer is extremely thin. The outermost 

 layer stains in this specimen darker than the middle, and has a bluish 

 tinge due to the haematoxyhn. Excepting for a single row of minute 

 black granules on its external surface, it is apparently structureless. The 

 middle layer stains only with the orange ; it is not homogenous, as it 

 contains in its entire thickness very numerous, minute, black granules. 

 There is no definite arrangement for these granules, and they are 

 equally abundant in all parts of the layer. The innermost layer is, as 

 already stated, extremely thin, and stains black according to this method. 

 I consider it to be structureless. 



Material fixed in Zenker's solution, but stained in the same way, does 

 not show as much detail. The outer layer is dark blue, taking almost 

 the same colour as the chromatin of the nuclei. It does not appear 

 homogenous, however, but seems to be traversed by fine pore-canals. 



In the middle layer the granules are not differentiated, the entire 

 thickness of the layer being almost homogenous ; very careful examination 

 shows, however, lighter spots corresponding to the granules, but as these 

 are very minute, they are extremely difficult to make out. The innermost 

 layer does not differentiate, or appears as a lighter orange hne between 

 the middle layer and the muscles running parallel to the cuticula. Material 

 fixed in formaline (4 per cent.), but stained in the same way, gives the same 

 results. The ciiticula of S. centripuvctata is smooth, unlike that of 

 S. hepatica, which is villose. 



TJie Suhcuticula. 



The subcuticula is best studied on not too contracted pieces fixed 

 with Zenker's fluid and stained with haematoxylin and orange g ; accord- 

 ing to the state of contraction or extension it, offers rather different 

 pictures. (Fig. 2.) 



