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. 3i. Chonetes sarcinulatus, the brachiopod to which the German coral Pleuro- 



dictj/um prohJematieum usually is attached. 

 Fig. 35. Vertical section of coral and tubes. 

 Fig, 36. The base of the Pleitrodictyum prohJematiciim attached to the brachiopod 



Chonetes 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. 



