curious Malformation in Taenia saginata. 115 



Some idea of the proportions of normal and abnormal 

 segments in this specimen may be gathered from the follow- 

 ing figures for a portion measuring about 70 cm. in length. 



Complete intersegmental divisions 70 



Imperfect intersegmental divisions 17 



Normally-divided segments with single pore (normal 



condition) 6 



Normally-divided segments with two opposite pores . . 46 



The first-mentioned kind of abnormality calls for passing 

 comment only. It is by no means uncommon in Teenia 

 saginata ; indeed, as Leuckart * remarks, " traces of it may 

 be seen in almost every chain." The commonest case is that 

 in which the division extends only a little way across the 

 width of the strobila. Sometimes it reaches to the middle 

 line, or beyond it. Owing to the divided side being longer 

 than the undivided side of the joint, the partial dividing-line 

 usually curves forwards somewhat before it disappears. This 

 forward curve may be carried so far that it meets the pre- 

 ceding intersegmental division, in which case a triangular 

 " supernumerary " segment is formed, wedged in between 

 two normal segments. Such " supernumerary " segments 

 may occasionally be the starting-points of the double, or 

 rather forked, chains of segments that are sometimes met 

 with. 



The second anomaly (segments with two opposite genital 

 pores) is more remarkable. Leuckart observed such segments 

 in T. saginata, but says of them f " here one finds behind 

 each opening a set of male and female .ducts, with cirrhus- 

 pouch and vesicula seminalis, but the reproductive organs 

 proper are as usual — the two vaginae passing into a common 

 shell-gland, and into a single uterus." In the present case, 

 however, further examination shows that the reduplication is 

 not confined to the pores and ducts — there are two complete 

 and bilaterally symmetrical sets of genital organs in each of 

 the segments with double pores. Each vagina has its own 

 distinct shell-gland, yolk-gland, ovary, and uterus. The two 

 uteri present a remarkable appearance in gravid segments 

 (see figure), running forward parallel to each other, and each 

 sending out the usual lateral branches. The branches on the 

 two inner, opposed sides of the uteri, however, have not room 

 enough for their normal development, and are stunted and 

 frequently unbranched, many of them containing few or no 



* ' The Parasites of Man,' English translation by W. E. Hoyle, 

 1886, p. 450. 

 t L. c. p. 451. 



