50 ORGANIC DEPENDENCE AND DISEASE 



Fig. 31. Etching of the basal part of the coral, showing the chief worm tube and 

 a wormlike extension which appears to arise from the base of a polypite and turn 

 into an upward course between the cells. 



Fig. 32. The greatly enlarged interior of a dead Hicetes tube encrusted with 

 slender serpulid worms. 



Fig. 33. A minute sponge found in the tube of the large Hicetes. 



Fig. 34. Clwnetes sarcinulatus, the brachiopod to which the German coral Pleuro- 

 dictyum problematlcum usually is attached. 



Fig. 35. Vertical section of coral and tubes. 



Fig. 36. The base of the Pleurodictyum problematicum attached to the brachiopod 

 Chonetex sarcinulatus. From Stadtfeld. 



Fig. 37. The tube Hicetes overgrown by polyp-cells of different series. 



Fig. 38. An etching of the coral showing an actual attachment of the worm tube 

 to the snail-shell Loxonema. 



Fig. 39. Vertical section of a coral showing the worm tube entrenched between 

 the polyp-cells. 



Fig. 40. An almost unique illustration of the attachment of the American 

 Pleurodictyum to the brachiopod Choneies eoronatus. 



