14 SIXTEENTH REPORT. 



that the pouches were shorter but thicker than those in which protrusion of 

 the cirrus had not taken place. Moreover in some cases the pouch was 

 greatly twisted in such a manner that its length was considerably reduced. 

 In the first group the cirri were well protruded. These pouches measure 

 0.216 by 0.12, 0.265 by 0.117, 0.265 by 0.093 mm., average dimensions 

 0.248 by 0.106 mm. In the second group of pouches the cirri were only 

 partly protruded. These pouches measure 0.283 by 0.11, 0.25 by 0.126, 

 0.20 by 0.146, 0.20 by 0.133 mm., average dimensions 0.233 by 0.128 mm. 

 The average of the seven pouches with protruded cirri is 0.239 by 0.119 mm. 



Comparison of the above data shows that while the cirrus-pouches of 

 nearly mature proglottids are only slightly shorter than the cirrus-pouches 

 of ripe proglottids with unprotruded cirri they are considerably more slender. 

 Comparison of the dimensions of the two classes of cirrus-pouches of ripe 

 proglottids, those with cirrus unprotruded and with this organ protruded, 

 shows that in the act of protruding the cirrus the cirrus-pouch is considerably 

 shortened, but its diameter may be slightly increased. The above data are 

 altogether too meager to permit the formulation of a general statement that 

 the act of protrusion of the cirrus is due to contraction of the walls of the 

 cirrus-pouch but this idea is strongly suggested. 



The unprotruded cirrus and the ductus ejaculatorius describe four or five 

 coils in the cirrus-pouch. When the cirrus is protruded this number is 

 reduced. Protruded cirri are first seen at the sixth centimeter. These are 

 readily visible to the naked eye. In all 26 such cirri were counted with 

 the aid of a hand-lens. In form the protruded cirrus (PI. 2 fig. 3) is some- 

 what cylindrical, slightly tapering from its base to its tip. Its length is 

 about 0.34 mm. and its breadth at the broadest part about 0.08 mm. No 

 coils of the ductus ejaculatorius are pushed out into the base of the cirrus. 



The vas deferens extends from the cirrus-pouch toward the median part 

 of the proglottid as a mass of coils which in nearly mature proglottids are 

 small and close. As the vas deferens becomes filled with spermatozoa its 

 walls are enormously dilated and the coils make a broad mass. 



Testes in nearly mature proglottids occupy two broad lateral fields (PI. 2 

 fig. 5) which extend latera almost to the vitellaria and mesad well toward 

 the median line but leaving between the two fields a free median zone. In 

 transections of the mature proglottid the testes are seen to lie in a single 

 layer in the medullary parenchyma. Testes number, in nearly mature 

 proglottids, from 107 to 160. These testes, which probably are not fully 

 , mature, measure about 0.066 mm. in diameter. They are spheroidal or 

 slightly irregular due probably to the juxtaposition of neighboring testes. 

 Four testes which were teased out of an unstained ripe proglottid measured 

 0.077 by 0.06, 0.083 by 0.077, 0.063 by 0.05, 0.067 by 0.057 mm., average 

 0.0725 by 0.061 mm. It was impossible to measure testes from fully mature 

 proglottids. 



In ripe proglottids (PI. 2 fig. 1) full of eggs only about 60 testes are visible, 

 lying laterad to the uterine pouches. In some ripe proglottids not more 

 than 50 testes may be seen. This is an apparent, rather than a real, diminu- 

 tion in the numl^er of testes. For in an examination of the ripe proglottids 

 with a lens magnification of about 465 many of the testes are found to be 

 reduced to one or tAvo large spherical cells. Such remnants are too small to 

 be seen when making the camera drawings with low magnifications. It is 

 moreover probable that a considerable number of the testes are covered up 

 by the great mass of eggs in the uterus. It is evident that the testicular 



