393] PSEU DOPEY LLIDEA FROM FISHES— COOPER 105 



threads. This sort of preparation is unfortunately not permanent, since 

 after a few minutes all of the canals disappear, excepting the very largest 

 which can still be followed as in ordinary toto mounts. The results of this 

 method of demonstrating the excretory canals are shown in figure 61, a camera 

 lucida drawing made while the canals were disappearing from view. Three 

 of Fraipont's large "canaux descendants" can be seen together with 

 much of the anastomes among them and at least two branches to foramina 

 secundaria. The largest and most median canal has a diameter of 50^. But 

 contrary to what was stated by Fraipont (1881:9,11), only six of these main 

 channels were found close to the ventral layer of longitudinal muscles in the 

 medullary parenchyma, and not six for each surface of the strobila. Lonnberg 

 stated, and correctly too, that their number is very variable as is their size 

 and course, the whole forming a compHcated reticulum showing the typical 

 "island formation." As regards the termination of the excretory vessels 

 at the posterior end of the strobila, the writer confirms Fraipont's (1881:10) 

 statement that: " Chez un sujet qui a deja perdu des proglottis, les gros canaux 

 longitudinaux sont rompus au niveau du bord libre posterieur du dernier seg- 

 ment. Les ims communiquent directement avec I'exterieur, les autres ne 

 sont renfermes et se terminent en cul-de-sac." But no cases were met with 

 in the material at hand in which it could be considered that no segments had 

 been lost. Towards the scolex the six vessels gradually come closer and closer 

 together until in the first segments they may appear for short distances in 

 two sets of three each, dorsoventrally situated; but farther on become lost 

 in their anastomoses. Entering the scolex there may be seen four, three, or 

 two main canals, but they cannot be followed as such thru many sections, 

 since they soon break up into the reticulum mentioned by Fraipont as ramifying 

 thruout the scolex. 



Of the generative organs the earliest writers were able to discern only the 

 external openings ("oscula") and the uteri which, showing their contained, 

 dark brown eggs thru the body wall as a longitudinal series of dark punctations, 

 gave origin to the specific names of Zeder (1800) and Rudolphi (1802 and 1810). 

 Concerning these characters Miiller (1788:6) wrote as follows: 



"Margines corporis depressi intersectione articulorum crenati apparent; 

 oscula in anterioribus articulis nulla adsunt, in posterioribus vera altera in 

 pagina port in macula albida nigricantes, in altera papilla alba subelevata, 

 punctaque seu globuli utrinque dispalati, qui ovida. Oscula seu pori non 

 seriem rectam in corpore. Taeniae sed hinc et illinc divergentem constituunt, 

 alterum in centro articuU, alterum in intersectione constituum. Articuli 

 postici reliquis latiores punctis utrinque dispersis medio autem coacer- 

 vatis papillullamque exhibentibus repleti sunt; horum coacervatio oculo nudo 

 punctum centri nigrum ofifert, armatus vero ovula seu globulos e membrana 

 ovata pellucida punctulis nigricantibus impleta constantes discernit. " 

 Rudolphi (1810:50) described them in these words: 



"Singuli enim articuli in superficie dorsali nodulum orbicularem, simpUcem 

 vel duplicem, subelevatum, vel albidum vel fuscescentem aut nigrescentem 



