Danaea and other Marattiaceae . 529 
strand (Centralstrang 1 , commissural strand 2 ) makes its appear- 
ance as a branch from the inner face of the more or less crescentic 
meristele, diagram IX, c.s. (cf. E. C. Jeffrey, Phil. Trans. B. 
Vol. cxcv, PL I, phots. 4 and 5). It traverses the ground- 
tissue, passing obliquely upwards (diagram X), joins the stelar- 
tissue of the opposite side usually at the same time as an 
incoming root (diagram XI). The leaf-gap is now closed, and 
there is what might be called a transitory solenostelic con- 
dition 3 . In Danaea this amphiphloic ring, with external and 
internal endodermis, has been found in all the seedlings which 
were old enough to have it, but it does not seem to occur at 
the corresponding level in each, nor is it so clearly developed 
in all. In most cases, moreover, there is a suggestion of an 
abortive attempt at its formation at a lower level. The 
central strand also may make an abortive attempt at forma- 
tion, as in one seedling it was found to consist of phloem 
only. Farmer and Hill 4 found exactly parallel conditions in 
Angiopteris. From the point of view of development it is 
important to note that the central parenchyma, with or with- 
out a mucilage-canal, is extrastelar in origin, and not con- 
tinuous with any parenchyma formed within the haplostele 
as a pith. In this, Danaea simplicifolia differs both from 
Angiopteris and A neimia phyllitidis 5 . A study of the micro- 
tome-series shows the mode of development clearly. As has 
1 R. Kuhn, Untersuchungen iiber die Anatomie der Marattiaceen und anderer 
Gefasskryptogamen, Flora, 1889, p. 463. 
2 Farmer and Hill, loc. cit., p. 376, par. 3. 
3 Fig* 3> Farmer and Hill, loc. cit., illustrates a distinct solenostelic stage in 
Angiopteris , for the leaf-gaps do not over-lap. It is impossible to decide from 
the text whether the tube is amphiphloic or not. In the latter case it would be 
what these writers call pseudosolenostelic. 
4 Loc. cit., p. 387, par. 1. 
5 L. A. Boodle, Annals of Botany, xiv, p. 389. After all, it may be only a difference 
in degree, through the reduction or loss of the central parenchyma in the case of 
Danaea simplicifolia , which is a very small plant compared to Angiopteris, in its 
seedling as well as in its adult condition. It might also be that it is Danaea , 
which is the more "primitive, and that the parenchyma, which in the first instance 
appeared simply to cut off the leaf-trace, grew to be a ‘ pith ’ for conducting and 
storing purposes as plants advanced in complexity and size. The writer does not 
feel competent to express any opinion as to which of these two views is the more 
rational. 
