CALCAREOUS SKELETON OP THE ANTHOZOA. 527 



Heider, Fowler, and myself. The fact is shown even better iu 

 a flat preparation of the edge-zone of Caryophy Ilia. The 

 desmocytes appear as a number of thick bands, corresponding 

 to the extra-thecal continuations of the mesenteries ; the 

 spaces between are occupied by the irregular vacuolated calico- 

 blasts which will be described further on. I may here insist 

 on the arguments which were put forward with great clearness 

 by Fowler (9). The lines along which the desmocytes occur 

 correspond neither to the septa nor to the costse, but in corals 

 in which there is a " pseudotheca" they correspond to the lines 

 along which adjacent septa have met and fused. These are not 

 lines of active growth, but contrariwise The regions of active 

 growth, the septa and costae, are not covered by desmocytes, but 

 by a quite different kind of cells, whose characters vary accord- 

 ing as the position is or is not one of active coral growth. The 

 position of the desmocytes affords strong presumptive evidence 

 against their being the active agents in coral secretion. Were 

 this the case the corallum would grow most rapidly not along 

 the edges of the septa or costae, but along the lines between the 

 septa and costse where the mesenteries are attached to it. But 

 these are exactly the places where its growth is least notice- 

 able. A few desmocytes, it is true, may be observed abutting 

 on the lateral surfaces of the septa. Such a one is shown in 

 fig. 27, on the left-hand side of the drawing ; but in such 

 places the desmocytes never form a continuous layer, but are 

 placed at intervals far apart from one another. 



A surface view of a group of desmocytes is given in fig. 35, 

 and a section made at right angles to their surfaces is repre- 

 sented in fig. 28. In the latter figure the strise are seen to be 

 dark branching fibres, which run with a wavy course from the 

 base to the surface of the desmocy te. These strise stain deeply 

 with iron heematoxylin, eosin, Bismarck brown, picro-carmine, 

 or picro-nigrosin. In fact, almost any diffuse stain will bring 

 them out. Neither their shape nor their staining properties 

 suggest their being spicular, as von Heider suggested, nor does 

 a surface view lend any further support to the idea. Viewed 

 from above, the desmocytes have a curious " machine turjied " 



