60 



s. GOTO. 



epithelial cells stain very sliglitly, are generally very clear, and are 

 also very much smaller than in Monocotijlc . 



Havin'T now described the various parts of the digestive system, T 

 shall proceed to note down a few considerations on the physiology 

 of the accessory glands. 



In the first place, as to tlie pharyngeal glands. vVs is well 

 known, there are in Turbellaria numerous unicellular glands in the 

 mesenchyma around, before, and bahind the pharynx. These open 

 mainly on the hps of the pharynx, but according to Lang^^ also on 

 the inner and outer surfaces. They have been called the salivary 

 glands. According to Graff-^, two sorts of these glands are to be 

 distinguished in Rhahdocoelida, viz., those that open into the mouth- 

 cavity (Pharyngealtasche), and those that open into the oesophagus 

 or, where such is wanting, between the pharynx and the intestine, the 

 latter sort alone deserving the name of " echte Speicheldrüsen." Those 

 who have had occasion to observe any turbellarian in the living 

 state will have noticed how hrmly it sometimes sticks to the side of 

 the vessel in which it is placed, by means of the pharynx and espe- 

 cially its lips, no doubt l)y virtue of the secretion of the " salivary 

 glands." Although I have not made any convincing observation on 

 this point, I believe the pharyngeal glands of Trislomum serve the 

 same purpose, and assist in attacliing the parasite securely to the host. 

 Again, in Dislomiim lanccolalum, unicellular glands with granular con- 

 tents open on the anterior border of the body. Their secretion is 

 regarded by Leuckart^^ as having " eine reizende Einwirkung auf 

 die GJ-ewebstheile des Wirthes." The numerous unicellular glands 

 that open into the ventral sucker and on both sides of the pliarynx of 



1). Lang— Die Polycladen des Golfes von Neapel, pp. Ill, 113, 115, 120. 



2). Graff— Monographie der Turbellarien. Rhabdocoelida. p. 99. 



3). Leuckart— Die menschlichen Parasiten. II Aufl., I Bd. II. Abtheil. p. 36t3-367. 



