Osborn . — Some Observations on the Tuber of Phylloglossum, 497 
masses. In one case (Text-fig. 16 a) this was all the development visible, 
but two of the others (Text-figs. 17 A and 18 A) showed in addition a minute 
white conical projection, arising from the cell mass and growing vertically 
into the soil. In one case (Text-fig. 18 a) rhizoids were visible arising from 
the cell mass close to the leaf. The fourth leaf (Text-fig. 19 a) showed 
a comparatively small cell mass, but from it there descended a cylindrical 
process, 2 to 3 mm. long, that terminated below the soil in a blunt apex. 
The structure resembled the stalk from which the new tuber of a Phyllo- 
glossum plant arises. 
By September 24 the leaf shown in Text-fig. 17 A had made further 
growth, the growing-point observed upon it having given rise to a descend- 
ing shaft. It was sketched (Text- fig. 17B) and fixed for microtoming. At 
the same time it was noticed that the leaf shown in Text-fig. 18 A showed 
two new features. First, the growing-point, already observed upon it, was 
distinctly bilobed ; second, from the upper surface of the cell mass, a minute 
green leaf-like process was emerging (Text-fig. 18 B). The further history of 
this leaf is shown in Text-figs. 18 c and D, drawn October 8 and November 16 
respectively.. The green process developed into a slender ‘ leaflet ’ 4-5 mm. 
long, whilst each growing apex developed a white tuberous body at the end 
of a short stalk. 
On October 8 two other leaves were found to have developed leafy 
processes, one of which is shown in Text-fig. 20 a. The figure also serves 
to indicate the extent of tuber formation by this date. There is a distinct 
stalk which carries the growing-point into the soil. The growing-point is 
swollen and whitish, but as yet quite smooth. The cell mass and such 
portions of the stalk as are exposed to the light are green. The presence 
of rhizoids upon the cell mass was found to be inconstant at this stage. 
Sometimes they could be distinguished, but more often they were absent. 
This, however, may have been due to injury, though every care was exer- 
cised in removing leaves for observation. Later, as will be seen, the tuber 
develops many rhizoids. 
On October 19 one leaf of the series, that had previously been 
observed to be changing to a dull watery green, was quite collapsed. It 
DESCRIPTION OF FIGS. ON OPPOSITE PAGE. 
Text-figs. 16-22. Leaves of Series B, detached and put on soil July it, 1918. The dates below 
in brackets are those on which the figures were drawn. All x 5J. Pig. 16 A. Cell mass forming 
(Sept. 16). Fig. 16 b. Same with adventitious tuber (Nov. 16). Fig. 17 a. Growing-point just visible 
on cell mass (Sept. 16). Fig. 17 B. Same, showing elongation of stalk (Sept. 24). Fig. 18 a. Cell 
mass with rhizoids and short stalk bearing growing-point (Sept. 16). Fig. 18 B. Same developing 
two growing-points from cell mass, also ‘leaflet’ (Sept. 26). Fig. 18 C. ‘Leaflet’ enlarged, two 
tubers forming (Oct. 8). Pig. 18 D. Same; tubers are smaller and less regular than those formed 
singly by other leaves of the same series. Rhizoids absent (Nov. 16). Fig. 19 a. Small cell mass, 
stalk, and growing-point (Sept. 16). Pig. 19 b. Same (Nov. 16). Fig. 20 a. Portion of leaf showing 
celf mass. Leaflet stalk and tubers beginning to i swell. No rhizoids at this date (Oct. 8). Fig. 20 b. 
Same original leaf beginning to rot (Nov. 16). Fig. 21 and 22. Two remaining leaves of series (Nov. 16). 
