268 HilL — On the Presence of a Parichnos in Recent Plants . 
Scott 1 has called attention to the occurrence in the mature seed of 
Lepidocarpon Lomaxi of two gaps, one on either side of the bundle, which 
are strongly suggestive of a parichnos, and mentions that a really sharp 
differentiation of this tissue is only found near the base of the sporophyll. 
Further, when dealing with the structure of the axis of the strobilus, 
he remarks the presence in the sporophyll of a strand of large-celled tissue, 
which probably represents the parichnos of the vegetative leaf base of the 
Lepidodendreae. 
Weiss 2 describes in Lepidophloios fuliginosus , a group of cells which, in 
connexion with each foliar bundle, passes through the outer cortex to the 
leaves where they form the so-called parichnos. 
Thus it is obvious that the parichnos was a tissue of wide occurrence 
in the fossil forms of the Lycopodineae, and that it occurred both in the 
sporophyll and foliage leaf. 
From a survey of the literature, still more so from the examination of 
the published figures, and from the actual preparations, one feature stands 
out with remarkable clearness, which is, that the different plants and 
specimens exhibit the parichnos preserved in very diverse conditions. At 
one extreme the tissue is represented by canals, as in the mature seeds and 
sporophylls of Lepidocarpon and Lepidostrobus ; at the other extreme there 
is a very definite parenchymatous strand as described by Williamson, 
Bertrand, Hovelacque, Seward 3 and A. W. Hill 4 , and others. In an 
intermediate position there are specimens showing the tissue in different 
stages of disintegration. 
This feature is capable of a simple explanation, which is, that these 
seeming discrepancies are due, in many cases, to the fact that the parichnos 
has been preserved in different stages of development : the empty canal 
being the mature structure. 
Whether this be true for all cases, palaeophytologists will be able to 
judge far better than the writer. 
Turning to what has been termed 5 parichnos in recent plants, it may 
be seen best in Isoetes Hystrix, 
The mature sporophyll of this plant exhibits two canals (Fig. i) running 
longitudinally, and situated, one on each side of the sporogenous mass, in 
1 Scott, D. H. The seed-like fructification of Lepidocarpon, a genus of Lycopodiadaceous cones 
from the Carboniferous formation. Phil. Trans. Roy. Soc. Lond., vol. cxciv, 1901. 
2 Weiss, A biseriate Halonial branch of Lepidophloios fuliginosus. Trans. Linn. Soc. Lona., 
2nd ser., Bot., vi, 1903. 
3 Seward, Notes on the Binney Collection of Coal-Measure plants, part i : Lepidophloios. Proc. 
Phil. Soc. Cambridge, x, 1899. 
4 Seward and A. W. Hill, On the structure and affinities of a Lepidodendroid stem from the 
calciferous sandstone of Dalmeny (Scotland), probably identical with Lepidophloios Harcourtii, 
Witham. Trans. Roy. Soc. Edin., xxxix, 1900. 
5 Hill, T. G., On the presence of Parichnos in Recent Plants. Brit. Assoc., Sect. K., 
Cambridge, 1904. 
