242 



CHILD. 



[VOL. I. 



Figure 21 . 



The figure represents four incompletely separated proglottids 

 seen from the ventral surface. Between a and b the furrows at 

 the left meet at the edge and extend over about one-third of each 

 surface, ending free. At the right a peculiar curved furrow 

 appears on each surface, and on the dorsal surface an oblique 

 furrow extends posteriorly over a from the curved position 

 almost to the posterior boundary of the segment. In accordance 

 with the relation of the furrows, the genital organs at the left are 



normal, but on the 

 right side of a b a 

 peculiar set of ab- 

 normalities appears. 

 Two distinct ovaries 

 and vitellaria, a' and 

 b', appear, one in a, 

 the other in b, but 

 there is only one vas 

 deferens, that in b. 

 The oviduct from a' 

 extends anteriorly 

 and unites with the 

 oviduct of b' near 

 the seminal recep- 

 tacle, and the com- 

 mon duct opens through the pore in b. In a number of cases I 

 have found two sets of organs opening through a common pore, 

 but the union of oviducts at a point so far from the pore is rare. 

 The organs a' consist wholly of female organs, the vas deferens 

 being entirely absent. It will be noted that the partial furrow 

 on the dorsal surface in this region takes an oblique course. 

 The right end of the curved partial furrow on the ventral surface 

 takes a similar course. The ovary a' lies quite near these fur- 

 rows and consequently there is no space for the development 

 of the vas deferens in anything like its normal position. As 

 the relative position of the various organs appears to be quite 

 definitely determined in all cases, there is probably no tendency 



FIG. 21. 



