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. Chonetes sarcinulatus, the brachiopod to which the German coral Pleuro- 
dictyum problematicum usually is attached. 
Fig. 35. Vertical section of coral and tubes. 
Fig. 36. The base of the Pleurodictyum problematicum attached to the brachiopod 
Clionetes 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 Chonetes coronatus. 
