On the conuective tissues and body cfivities of the Nemerteans. 29 



either as exceediugly fine, scarcely disceruible granules in the cells; 

 or as comparatively large, homogeneous grains, possibly rejjresenting 

 fused masses of fine granules, since usually only one such large grains 

 occurs in a cell. 



b) Cells between the outer and inner neurilemma, in the lateral 

 nerve chords. Similar to a), but devoid of pigment. 



c) Cells on the periphery of, and within the fibrous core, in both 

 brain and lateral nerve chords. These cells are as a rule unpigmented, 

 but a small percentage in the brain lobes showing evidences of pig- 

 ment. They differ from the two preceding forms in that their nuclei 

 stain more intensely. 



Bürger ('90) has described a pigmented intracapsular tissue for 

 DrejpanopJiorus, of similar structure and distribution as my modification 

 a). He mentions, further, other pigmented elements, which are not 

 present in any of the species examined by me: "Endlich finden sich 

 im Gehirn und den Seitenstämmeu rundliche, sehr dichte, gelbe 

 Pigmenthaufen von verschiedener Grösse. ... Sie sind nicht mit den 

 Pigmentzellen des Hüllgewebes [i. e. intracapsular tissue] zu ver- 

 wechseln, da sie nie Verästelungen zeigen, sondern immer compact 

 erscheinen und statt der grossen, blassen Kerne sehr zahlreich äusserst 

 minimale, dünne, kurze Kerne eingelagert besitzen, welche sich intensiv 

 tingiren. Solche Pigmenthaufen finden sich aber auch an andern 

 Orten im Nemertinenkörper" etc. (1. c. p. 221). 



5) An interstitial connective tissue of the body 

 epithelium I have been unable to find; and it is probably absent, 

 since the bulky, haematoxylin-staining gland cells of the epithelium 

 lie so closely together, that no noticeable space remains for such an 

 interstitial tissue ^). 



VI. Amphiporus virescens Verr. 

 1) Branched connective tissue cells, with inter- 

 cellular substance. General distribution of this tissue, as in 

 Ä. glutinosus; but in virescens the fibres are more pronounced, and 

 between them less intercellular substance is present, so that the tissue 

 stains deeply with haematoxylin. In the basal membrane of the 



1) These slime cells are larger and more numerous in A. gluii- 

 nosus than in any Nemertean with which I am acquainted ; and dis- 

 charge that thick and viscid secretion, which forms the characteristic 

 covering of this species. - 



