100 



LUCERNARI^ AND THEIR ALLIES. 



luuliffcrentiated from the nucleus. Their distal ends lie in close contact and 

 thereby luive beconie polyyoiiul, and present the appearance of an irregular net- 

 work when this stratum is seen from either of its faces (./7^. 106). We must not 

 omit to mention, also, that the cell-membrane is ribbed lengthwise {fig. 107) witli 



the cell. 



197 (A). Another peculiarity in the disposition of these cell-fibrillfe explains 

 the apparent subdivision of the chondrophys into three layers {fiys. 82, 83, c, c\ 

 c'). Where their ends are crowded together their membranes become partially 

 fused into each other, and seem to lose their refractive power, and become more 

 transparent; so that tlieir outlines are exceedingly faint. Now if we observe care- 

 fully, we may see that they are applied against each other to a certain length, 

 forming thus a sort of pavement-work, of a definite depth, and then they all 

 together, along one horizon, abruptly separate from each other and taper off toward 

 their mid-length. The pavement-work, then, at each end of the fibrilla?, corresponds 

 to the two pale subdivisions {c\ c) of the chondrophys (see ^ 186), next the gas- 

 trophragma and the ectophragma, and the middle sirbdivision, to the region in 

 which tJie fibrillae are tapered down to a slender waist. The finer and parallel 

 striation in the two pale subdivisions is due to the longitudinal ribs of the fibre- 

 cells. The outermost subdivision is at most not more than one-third as thick as 

 the inner one,* and becomes obliterated in the advanced stages of growth, by the 

 retraction of the parietcs of the fibre-cells until they cease to touch each other, 

 except at their extreme termini, where they abut against tlie cells of the ecto- 

 phragma. That these fibre-cells are not fibre-like hollows, or plications of the 

 amorphous hyaline substances, is proved by an inspection of a cut surface of the 

 chondrophys, made by a section through its thickness, when the fibrillfe will be 

 found more or less curled or bent, and projecting loosely {fig. 83, c'^) from the 

 matrix in which they were developed. 



197 (B). The size of the fibre cells varies considerably, but within certain limits. 

 They are never so small as to cover less than three or four of tlie cells of the walls 

 upon which they rest, and sometimes they extend over half a dozen of them. In 

 this case, then, they cannot have been developed within any of Virchow's " cell- 

 territories," to say nothing of other, reasons, given above, why they could not 

 have originated thus. As a general thing they extend directly through the thick- 

 ness of the chondrophys from the gastrophragma to the ectophragma; but there 

 are some modifications of this at certain points. We have shown in a previous 

 section (^ 67) that, at the partitions of the umbella, the chondromyoplax and 

 the cliondrophys lie in immediate contact ; the gastrophragma failing here. Con- 

 sequently the proximal ends of the fibre-cells of the chondroi)hys {fig. 83, c') abut 

 against the inner ends of the fibrillse (fibre-cells !) of the chondromyoplax {h"). At 

 the edge of the umbella, along the intertentacular margin and at the base of the 

 tentacles, the distal ends of these fibres abut against the muscular partition (>>. 

 60, 61, 62, /.-'), which separates the border of the chondromyoplax from that of the 

 chondrophys. At the anchors (colletocystophores) it appears that the liroximal 

 ends of these fibres abut against the muscular partition {fig. 83, ¥). If now there 

 were any derivative connection between these fibres and the adjacent walls, they 



