674 PROF. MIXCHIN AND DK, KEID ON THE [June 16, 



Addendum. 



Intracellular Netivorks in the Gastral Layer. 



A point of some interest was observed in a preparation made 

 in the following manner. A piece of the body-wall of Clathrina 

 contorta (preserved in alcohol) was stained with picro-nigrosin, 

 and passed through water and alcohols into oil of cloves ; then 

 •jhe inner gastral surface was brushed gently with a soft paint- 

 brush to remove the gastral layer of collared epithelium ; finally, 

 the piece was mounted in Canada balsam with the gastral sui-face 

 uppermost. The upper surface of the preparation then showed a 

 delicate honeycomb-like network, stained blue with the nigrosin, 

 enclosing irregvilar polygonal meshes fairly uniform in size, with 

 here and there a much larger rounded mesh and occasionally a 

 small, circular mesh. As the preparation was not all in one 

 plane, only small stretches of the network could be sharply 

 photographed (fig. 24, PI. XXXVII.). The polygonal meshes 

 represent spaces formei'ly occupied by collar-cells, many of which 

 are to be seen still in situ in the prepai-ation ; the large rounded 

 meshes are spaces left by porocytes ; and the small circular 

 meshes are shown by their relations to underlying triradiate 

 systems to be the spaces occupied by the gastral rays of quadri- 

 radiates. The network itself is an extension of the gelatinous 

 ground-substance between the bases of the collar-cells and gastral 

 rays and round the inner ends of the porocytes, probably forming 

 a cementing substance, as it were, helping to keep the easily 

 detached collar-cells in their places. 



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