NO. 1780. 



A NEW CESTODE PARAISITE—HALL. 



143 



The female reproductive system shows no notable pecuHarities 

 in the mature proglottid. From the genital pore the vagina swings 

 in a wide curve to the neighborhood of the shell-gland, where it opens 

 into a small receptaculum seminis. Around the shell-gland the 

 ovaries are arranged in somewhat crescentic 

 fashion, and the vitelline gland lies partly pos- 

 terior to the median portion of the ovaries. 

 The uterus outline in the mature proglottid 

 is not shown in figure 5, owing to its failure 

 to stain differentially. 



Gravid proglottids, collected from the feces 

 and mounted in glycerine jelly, measure 5.5 to 

 8 mm. long by 2 to 2.5 mm. broad. One 

 mounted in balsam measures 10.5 by 4 mm. 

 broad. In the gravid proglottid the uterus 

 develops a form somewhat different from that 

 typical of the genus Tsenia. Originating as 

 a median longitudinal stem, it develops at 

 times branches of unusual form, quite unlike 

 the more uniform and regular branches of the 

 commoner mammalian cestodes of the genus 

 Tsenia. An illustration of this unusual 

 branching is given in figure 6. Usually the 

 median stem enlarges greatly, and the nu- 

 merous club-shaped lateral branches are so 

 closely approximated and at times so united 

 that the ultimate result resembles a lobed sac 

 filling the proglottid between the lateral and 

 transverse excretory canals and the muscular 

 layers. (See fig. 7.) A striking peculiarity is 

 the formation in many proglottids of a uterine 

 lobe which at the genital pore extends out over 

 the lateral excretory canals to a variable dis- 

 tance. (See fig. 8.) In two cases noted, this 

 lobe extended to within 134 /( of the tip of 

 the genital pore. The lobe in question occu- 

 pies a position close to the cirrus ]30uch and 

 vagina, and these appear to be compressed 

 or crowded aside by this uterine growth. The 

 appearance of the segments suggests that 

 there is an area of weakness in the vicinity 

 of the genital pore, and that the growing uterus has profited by this 

 weakness to make an excessive growth at the point occupied by the now 

 useless and partly atrophied genital canals. A large number of the pro- 

 glottids obtained from the feces of the dog showed the uterus empty or 



'#T 



[ 



tmin. 



Fig. 8.— Margin of proglot- 

 tids WITH developing EGGS 

 IN UTERO. 



