LUCE RN A RLE A N D T H E I R A L L I E S. 107 



upon the cells, not exactly parallel with the axis of the tentacle, but oblitjuely to 

 it, (xnlrifwjally, and lience, as a proof of it, we liud the same cells, which were not 

 quite twice so deep as broad when the tentacle was extended (/*/. 90, ?i'), are h(>re 

 ( /iy.s. 92, 93) at least five times deeper tlian broad, that is, they are very narrow, 

 and moreover, frorn mutual pressure, prismatic in appearance, when viewed in a 

 body. 



202 (B). It is well worth while to observe that, when these cells deepen, 

 the change appears to be confined mostly to that region which lies between the 

 nucleus (rf') and the end next the muscular fibrillar (jiv), while the modification at 

 the other end consists of little else than a narrowing in one direction, and a broad- 

 ening at right angles to that. Why the nucleus marks these limits we cannot 

 conjecture ; and although it may be readily understood why the cells should deepen 

 more at the proximal end, that being nearer in the line of the pressure induced by 

 contraction, there is no apparent reason why there should be such a sudden change 

 on the distal side of the nucleus, where the depth increases very little. When the 

 tentacle is fully extended the nucleus (^fiijs. 90, 91, d') of the ectophragmal cells is 

 a little nearer to the distal than to the proximal end. Between this condition and 

 that of extreme contraction of the tentacles there are to be observed all possible 

 grades within a short space of time; there is no absolute standard of proportion in 

 any part of the shaft of these organs. In their spheroidal tips, however, tlie cells 

 of this layer (^j/-'?. 88, 89) seem to have been crystallized, as it were; fixed within 

 extremely narrow limits of change, and varying but slightly in depth, wliich is to 

 their average breadth as five or six is to one. But of this we sliall speak hereafter 

 more in detail. 



202 (C). Contents. — The ectopliragmal cells of the shaft {fi<js. 90-93, ?«') are 

 very transparent, not only as regards their contents (t/-), which are perfectly homo- 

 geneous, but as to their walls (</). The latter are moderately thick, evidently ; 

 although it is quite difficult to detect the line of mutual apposition of adjacent 

 walls, which is still more uncertain at those places where interstitial granules (e'-) 

 are crowded between them, or overlie their peripheric or proximal ends. Beside 

 this very abundant and more or less highly colored, interstitial, granular substance, 

 there are scattered here and there, quite rarely, isolated ncmatocijsts (/). The 

 nucleus (tZ') lends little or nothing to the color, as it is of a grayish transparency ; 

 but still, it is readily detected, on account of its peculiar, soft, semi-opacity. It is 

 rather oval than circular in j)rofile, and might be compared to a slightly flattened 

 disk, attached by one of its faces to the cell-wall. Its greatest breadth is fully 

 three times the thickness of that wall. 



203. Tlie ectoplirmjma of the spheroidal tip (nematocystophorc) of the tentacles 

 presents some peculiar modifications not to be found on the shaft. This is the part 

 which is formed first {fi<js. 58, 59, <^-) in a young tentacle, and may be recognized, 

 even before the organ amounts to more than a mere papilla, by an accumulation 

 of numerous nematocysts imbedded in the interstices of the cells, and also by an 

 extraordinary deepening of these cells, so as to give an abrupt increase to the thick- 

 ness of the layer. Even at this early period the cells are three or four times deeper 

 than broad, and they continue to develop in tliis respect until the tentacle is full 



