OF THE FOSSIL PLANTS OF THE COAL-MEASUEES. 
63 
outer cell. That the latter breaks up when matured, is undoubtedly true. In a 
ripe strobilus the difficulty is to find a spore of which this layer is not broken up. But 
in none of the fragments do we discover the four club-shaped organs known as elaters. 
I have in my cabinet thousands of these spores, but in no solitary instance have I found 
a true clavate elater. On the other hand, I think I have abundant evidence that what 
Mr. Carruthers regards as such are but the shreds of the mother-cells which were 
derived primarily from the interior of the sporangium-wall. An examination of true 
Equisetiform spores during their development, and a perusal of the records of the same 
process as it is described by Hoffmeister and Sachs, tend to confirm my view ; not that 
any exact parallellism can be traced between the fossil spores and those of the living 
Equisetum ! far from it ; but we do find in the one the broad outlines of what may have 
taken place in the other, as in many varied cryptogamic growths. Be this as it may, I 
affirm unhesitatingly that had the outer wall of the fossil spore ever resolved itself into 
true elaters, we should see their spiral lines, as they are accurately represented by 
Sachs*, crossing the circular disks of the spores in innumerable instances. The tissues 
of which these spiral bands consist are precisely such as would be likely to be preserved, 
and be conspicuous, in the fossil state ; whereas, I repeat, no one has ever pretended Jo 
have seen them in this condition in any solitary instance. 
The correctness of my explanation receives further support from the spores of a stro- 
bilus in my cabinet which has not attained to its full maturity. Four of these spores 
represented to the right of the group (Plate VII. fig. 43, w', w") will be recognized by their 
smaller size and darker tint. Their inner spheres especially are little more than half 
the size of those constituting the rest of the group, and their outer cell-walls are as yet 
unruptured. We have here the precise stage of growth in which the transverse spiral bands 
should be conspicuously present ; and from this stage up to the final disruption of the cell 
they ought to become increasingly obvious, but nothing^of the kind is to be seen. In 
every instance we have a simple cell-wall of uniform density, instead of that alternation 
of thick and thin bands, the formation of which precedes the liberation of the former 
as true elaters. In addition to this negative evidence, some of these specimens exhibit 
testimony of a positive kind. It must be remembered that elaters are formed out of the 
outer investing layer of each individual spore ; but at w' I have represented two examples 
in which each outer cell-wall encloses two distinct spores — a condition that would have 
been genetically impossible had these cells represented the outer layers of individual 
spores, as is necessary on the elater hypothesis ; but on the supposition that they are 
mother-cells almost every difficulty disappears. Sachs correctly describes the mother- 
cells of Equisetum as 44 ceasing to be a continuous tissue, and not only isolating them- 
selves, but floating freely in a liquid, filling the sac of the sporangium” {loc. cit. p. 355). 
The disputed structures appear to me to have originated in some similar manner ; and 
what Mr. Carruthers has described as elaters I believe to be merely fragments of their 
irregularly torn cell-walls, which naturally broke up when the contained spores became 
* Lehrbuch, fig. 280, C. 
