STUDIES OX THE ECTOPARASITIC TREMATODES OF JAPAN. I55 



des Laurer'schen Canals in den Dottergang bai Distoimim hepaticum" 



Leuckart'^ resfards the ofenito-intestinal canal as homoloorous 

 with the Laurer's canal and applies this name to the former. He says, 

 " Die Scheide von rohjstomum integcrrhmim evachént hiernach als ein 

 Gebilde, welches, da es neben dem Laurer'schen Kanäle existirt, dem- 

 selben nicht homolog sein kann." ITe is of the opinion that the 

 supposed (by Lorenz) opening of the genito-intestinal canal into the 

 vitellarium can no more be regarded as an objection against his view 

 than that the unpaired condition of the vagina in certain monogenetic 

 ïrematodes can be advanced as an objection against its homology 

 with the paired vagina of rohjstoniwn. "Jedenfalls," he warns us in 

 conclusion, " ist das, was man bei d^n Trematoden als Scheide 

 bezeichnet, nicht ohne YVeiteres überall als dasselbe Gebilde in An- 

 spruch zu nehmen und als Laurer'scher Kanal zu bezeichnen." 

 Leuckart is inclined to reijard the Laurer's canal as bein"; homo- 

 JofTfous with the vagina of the Cestodes. 



AY right and Macalluni"^ after describing the canal in Spliy- 

 ramira, say, "How such an ec(3nomical method of disposing of sur- 

 plus yolk can have been arrived at, whether by the modification of a 

 Laurer's canal or otherwise, we are unable to say." 



Monticel 1 i"'^ : " Lasciando induscussa la questione, se serve o no 



il canale di Laurer come organo di accompiamento, giudicando 



ora la cose dal punto di vista puramente morfologico, io credo, come 

 del resto parmi pienamente giustificabile, che il canale di Laurer dei 

 digenetici per la sua posizione e il suo decorso, per i suoi rapporti con 

 I'ovidotto interno e con gli organi femminile in generale e per la 

 presenza di uno slargamento vesicolare, paragonabile al ricettacolo 



1). Leuckart— Parasiten, II. Aufl., 1. Bd., 1886, p. 58-59. 



2). Wright and Macallum— Sphyranura Osleri. Jonrn. of Morphology, Vol. I, 1887, p. 42. 



3). Monticelli— Saggio, 1888, pp. 58-59. 



