ox DIPLOZOOX NIPPOXrCUM, X. !SP. 167 



thick and niu.sriihir. The luiisciiJar übres are mostly arranged meri- 

 dionally, i. e. if we suppose the ventral and dorsal pole of the gland 

 to correspond to the two poles of the earth, the muscular libres are 

 arranged nearly in the plane of the meridians. Fibres also come 

 from the dorsal side of the animal, and enter the wall. ]>et\veen the 

 muscular fibres, I have sometimes observed nuclei, which are to all in- 

 tents and purpose exactly similar to those of th^ general mesenchyma 

 of the body, and probably belong to it. 



IV. The lYIesenchyma. 



Ut" the mesenchyuiatous connective tissue of the Trematodes, 

 Leuckart^' distinguishes two forms. In the Hrst torm, the mesen- 

 chyma consists of a "fast homogene helle und feinkcirnige Substanz 

 mit zahlreich eingelagerten kleinen Kernen '" ; in tlie second ioviu oi 

 the mesenchyma, \ve see "' Zellen von mehr oder minder ansehnlicher 

 • rrösse, die îuit einer meist wasserhellen Masse gefüllt sind ' and 

 generally of a polyhedral form, with a tibroiis net- work between. 

 Taschenberg"' regards the mesenchyma " als ein Bindegewebe, wel- 

 ches zu einem Maschenweike entwickelt ist, in welchem die urs})riing- 

 lichen Bildunuszeilen iheilsnoch \'orhanden sind, tlieils aljei' nur an 

 dein Proto[)lasnia mit darin eingelagerten Kernen sich erkennen 

 lassen." All these forms of the mesenchyma, however different they 

 may seem U) be with one another, can. in m\ (ipini(jn, l)e deri\'ed 

 from the dilferentiation in different- directions of a single primiti\e 

 fjrm. fhe strong resemblance of the mesenchyma of the Trematodes 

 to the chorda dorsalis of the \ ertebrates lias already been observed by 

 i.euckart ; and I 1)elieve the former is formed jn.st in the same manner 

 as the latter. But first the mesenchyma oî Dlplozoon. 



]) Leuckart — Die Parasiten des Meuschen. It. Auflaj^e. I. Bd. 3. Liefg. p. 13 et seq. 

 3) Tasehenberg — 1. c. p. 13. 



