125 



club-shaped structures, thickest at the outer end, staining hghtly with 

 haematoxyhn, total length about 4-^- ij., thickness perhaps ^ fj, or less. 

 (Zenker, haematoxylin, orange g, 40 cm. from scolex.) 



The Genital Appaeatus. 



The first trace of the genital apparatus can be seen in total prepara- 

 tions at a distance of about 1 cm. from the scolex ; here one notices a 

 narrow unbroken band of darker stained tissue running down the chief 

 axis of the strobila ; this band becomes more distinct by the time the 

 10th cm. from the scolex is reached. Between the 12th and 20th cm. the 

 testes begin to appear, filling the dorsal portion of the field between the 

 ventral canal and the lateral nerve, and between the ventral canal to just 

 beyond the dorsal canal ; there is no space for testes dorsally to the 

 ventral canal. The central dark stripe also begins to lose its continuity 

 and to break up into a series of transverse lines. Between the 20th and 

 30th cm. a great deal of development takes place. The median dark 

 stripe disappears, the testicles become much more conspicuous, occupying 

 the outer quarter of the median field, but not passing the nerve laterally. 

 In each segment one now sees a dark strip of tissue, irregularly alternating 

 to right or left, commencing just before the median line, slightly swollen 

 at its internal end, clearly traceable as far as the lateral canal ; very care- 

 ful examination shows these transverse lines of tissue to be continued to 

 the opposite side by a very fine canal, running to the testes {vas differens). 

 At 40 cm., the testes remaining as they were, these strips of dark staining 

 tissue have still further developed. Just to the right or left of the median 

 line, according to whether the segment opens to the right or left, very 

 distinct round clumps of tissue are seen (ovaria) ; to each side of these 

 ' clumps the dark tissue becomes fusiform and stains less darkly ; it is con- 

 nected by a mere thread across the ventral canal to the anlage of the 

 vagina and cirrhus apparatus, which lies as a long, shghtly pointed strip between 

 the ventral canal and margin, without, however, reaching the margin. At 

 50 cm. the chief difference seen is that the cirrus has somewhat approached 

 the margin, which is reached at 60 cm. At 70 cm. we notice the anlage 

 of the uterus crossing the median field. As the uterus becomes larger 

 and broader and fills with eggs, the ovary atrophies and finally disappears 

 from view on total preparations about 40 cm. further on. (The exact 

 distance cannot be given, as the specimens studied consist of various 

 fragments.) At about 95 cm. from the scolex a strip of dark staining 

 fibrillar connective tissue begins to develop between the uteri of every 

 two consecutive segments, firmly holding them in position. At 130 cm. 

 from the scolex, the uteri have increased still more in size, and in con- 

 tracted material three or more segments can be seen to pass over a single 

 uterus ; that is to say, the uterus of each segment bulges into the two 

 adjacent and sometimes even into still more distant segments. At this 

 stage WolfihiigeFs " Faserknaeiiel " {Stilesia hefatica, p. 10), is to be seen 



