90 



to radiate from the surface of the cell towards the duct. They appear 

 to be the same structures which were detected by Heidenhain in the 

 epithelial cells of the convoluted tubules of the Mammalian kidney. 



The cells constituting the various lobes of the nephridium are 

 bound together by fibrillar connective tissue beneath which one blood- 

 vessel (possibly a second also) derived from the great lateral trunk pe- 

 netrates and breakes up to form a marvellously complete plexus, its 

 branches running between the contiguous nephridial gland-cells. 



I have not been able to detect any stroma-tissue in the nephridia 

 nor to determine the cellular structure of the walls of the blood-vessels. 

 The w^alls in question are distinct enough^ and the natural injection 

 of the plexus and dilatation of the vessels varies in different specimens. 



A prolonged examination of the nephridia of Hirudo by various 

 methods, has served to confirm the usually accepted opinion viz. that 

 the duct has no communication with the body-cavity. 



Epithelium and walls of the alimentary tract. The 

 cells which line the coeca of the alimentary tract of the medicinal Leech 

 are remarkable. They are not ciliated, nor are they columnar, but are 

 short hemispherical cells 'with pale nucleus around which are nume- 

 rous coarse granules. During digestion (as shewn in transverse sections) 

 they one and all give origin to a secretion which stands forward on the 

 top of each cell as a hyaline, homogeneous drop of viscid consistence, 

 compressed and elongated by the viscid drops adjoining it. It will be 

 interesting to compare these cells with those in the corresponding region 

 of Aulostomum in which the material to be digested differs very consi- 

 derably from blood. 



The muscular fibres in the wall of the alimentary canal are band- 

 like and arborescent — often terminating in a stellate group of pro- 

 cesses. 



Clear-walled blood-vessels (quite independent of the botryoidal 

 tissue) form a plexus in the wall of the alimentary canal. 

 January 24th, 1880. 



3. Beiträge zur Kenntnis des anatomischen Baues der Geschlechtsorgane 



bei den Phalangiden. 



Aus dem Zoologischen Institute in Amsterdam. 

 Von J. C. C. Loman, Cand. Phil, in Amsterdam. 



Auf Veranlassung der »Beiträge zur Kenntnis des anatomischen 

 Baues der Geschlechtsorgane bei den Phalangiden« vonH. W. de Graaf 

 in No. 47 des Zoolog. Anzeigers, theile ich die Hauptresultate mit, 

 welche ich bei der Beantwortung derselben von der pilosoph. Facultät 

 der Universität zu Leiden gestellten Preisfrage erhalten habe. 



