DAVID B. SLAUTTERBACK 83 



trioles at the opercular end, and the Golgi complex aggregated 

 around the open end of the nematocyst. 



Figure 17 illustrates a very recent observation in our laboratory. 

 The micrograph shows a cross section of the neck region of a devel- 

 oping nematocyst. The accumulation of vesicles of the Golgi complex 

 indicates the forming tul:>e has not yet extended very far out of 

 the capsule. Immediately surrounding the Golgi membrane, which 

 encases the nematocyst, is a row of very small tubules. They are 

 about 180 A in diameter with a lumen about 75-80 A in diameter 

 and a wall thickness of al)Out 50 A. In the upper right quadrant of 

 the figure they are seen in perfect cross section. The function of 

 these elements is not yet clear, but some of their structural relation- 

 ships may be significant. In the interstitial cells they are found in 

 groups scattered through the cytoplasm. Within the groups tubules 

 are arranged at right angles to each other. They are evidently contin- 

 uous with the tubules which have been interpreted as spindle fibers 

 in Figure 8. In intermediate stages they are as figured here and in 

 later stages (as Fig. 27) they continue to surround the nematocyst, 

 oriented parallel to its long axis and are continuous at one end 

 with the rootlets of the stiff rods ( described later in this paper ) and 

 at the other with dense coils of tubules in the nuclear zone and seen 

 as fibrous bodies in Figure 27. The only suggestion of function 

 is seen in the relationship at the arrow in Figure 17. Here one 

 tubule appears to be in direct communication with one of the small 

 spherical vesicles of the Golgi complex. Whether this indicates a 

 separate mechanism for the production of nematocyt capsule is not 

 yet clear. 



Now to return \ er\' briefly to the endoplasmic reticulum. Figure 

 18 shows a fairly earh' group of cells with small tubular elements 

 of the reticulum. In Figure 19 you will see a fairly late stage in the 

 development of the cnidoblast. The cell has about reached the peak 

 of its synthetic activity, and the endoplasmic reticulum now assumes 

 a more packed formation and you see many flattened sacs which are 

 disposed in a concentric array around the nucleus. The wider spaces 

 (also marked with a star in Fig. 20) are areas where the reticulum 

 has been cut obliquely and are not in reality such wide diameter 

 structures. And finally the condition illustrated in Figure 20 is 

 reached when the reticulum fills most of the cell. During the fomia- 



