Osborn . — Some Observations on the Tuber of Phylloglossum. 5 1 1 
length and the new tuber was appreciably swollen, showing that considerable 
plastic material had been transferred to it. By the latter date the leaves of 
the growing plant were presumably depleted, although they did not appear 
senile, and the phase at which regeneration could be successfully accom- 
plished was nearly over. 
In regeneration a cell mass is invariably formed first. Upon this 
a growing apex usually differentiates, from which the starch-containing 
tuber develops. But in some cases no apex is formed and the cell mass 
itself becomes starchy as the growing season concludes (Series A and E). 
Thus the cell mass may, under some circumstances, behave as a perennating 
organ. The essential feature of the cell mass is that it is a roughly 
spherical structure, in which carbohydrate material may accumulate, but 
which is capable of producing further growth after differentiating a growing- 
point. The occurrence of a ‘ leaflet ’ upon the cell mass is variable. In 
Series E two of three leaves developed one, but in Series B the three leaves 
that did so produced the ‘ leaflet ’ only after a considerable amount of 
adventitious growth had taken place. This suggests that the ‘ leaflet * is 
a structure of secondary importance, produced in response to some such 
physiological stimulus as a failing or insufficient carbohydrate supply. 
The cell mass is, as it were, the first foothold secured by a young plant, 
a starting-point from which further developments may occur, circum- 
stances being favourable. Small parenchymatous swellings containing 
starch are not uncommon amongst minute plants in regions of rapidly 
varying humidity. A species of Fossombronia growing beside Phyllo- 
glossum has a thallus with a markedly swollen midrib. The tubers of 
certain Australian species of Anthoceros are well known. Near to the 
locality in which Phylloglossum occurs, A?iogramme leptophylla grows in T 
abundance. This has a peculiar prothallus with a small, starchy tuber . 1 
Bearing in mind the climatic conditions under which it grows, the 
early and constant production of a cell mass gives special interest to the 
behaviour of regenerating leaves of Phylloglossum , and to any comparison 
that may be made between them and those of certain species of Lycopodium. 
Cases of vegetative reproduction in the genus Lycopodium are well 
known, the example of adventitious shoots produced by the first leaves 
of embryo plants of Lycopodium inundatum cited by Goebel 2 being of 
special interest in considering the behaviour of Phylloglossum. Our know- 
ledge of vegetative reproduction and regeneration within the former genus 
has been considerably extended of late by Holloway . 3 Specially valuable for 
comparison with the structures described in Phylloglossum are the gemmae 
produced from old roots and from detached leaves of L. ramulosum . The 
. gemmae 4 formed from detached fragments of roots are stated to arise from 
1 Goebel, K. (1905) : p. 216. 2 Goebel, K. (1900) : p. 46. 
3 Holloway, J. E. (1916) • loc. cit. 4 Loc. cit., p. 85. 
