104 
Tjie Rot in Sheep. 
tepid water. The creature almost immediately elcAated its head, 
and, with a leech-like action, ejected a portion of the contents. 
This was quickly followed by two other similar ejections, soon 
after which it died. Since that time we have witnessed the 
same thing again and again, for it has always been our object to 
obtain the entozoon alive for our investigations and dissections. 
That a strong opsophagean sphincter is required can be easily 
understood, when it is remembered that on the creature having 
forced itself into the smaller ramifications of the biliary ducts, 
the pressure exerted on its body by the peristaltic action of the 
ducts is at times very considerable. This pressure might other- 
wise drive out the alimentary matter from the digestive organs. 
In dead flukes the sphincter is still so firmly closed that, 
although by pressure between two plates of glass under the 
microscope, the alimentary materials are easily driven backwards 
and forwards and made to press against the lower part of the 
ccsophagus, none can be seen to be expelled through it into 
the mouth. The free passage of the contents of the digestive 
organs in either direction shows, however, that every facility is 
given for the oral sucker to act either as an inlet or outlet to 
the digestive system. 
Generative Organs. — The reproductive system is without doubt 
by far the most interesting portion of the organization of the di- 
stoma, but at the same time it is the most complex in its arrange- 
ment, and difficult of investigation. This arises from the circum- 
stance that the entozoon is hermaphroditic or bi-sexile, and as a 
necessary consequence the male and female organs are inter- 
mingled to some extent, while their naturally large development 
requires their occupancy of a considerable portion of the body of 
the creature. In the illustration {fig. 7) inserted overleaf, the 
generative organs are represented apart from any others — an 
arrangement which will materially assist our description. We 
shall first explain the several peculiarities of the female organs, 
and follow with those of the male. 
Female Organs : the Vitelligencs, or yelk-forming organs (a a. 
Jig. 7). These structures occupy the margins of the body on 
either side, extending from about opposite the inferior portion of 
the ventral sucker to the extreme end of the distoma. The yelk 
sacs are clustered around minute tubes in the form of branches, 
somewhat like currants upon their footstalks, giving a beautiful 
dendritic character to the whole arrangement. The stems of these 
tubes are in turn connected with two larger ducts, h h, which run 
more or less in a wavy course parallel with the margins of the 
entozoon. These collect the contents of the smaller tubes, which 
they transmit by two horizontal branches, c c, to an ovoid body 
situated in the centre of the creature at about its upper third. 
