A natomico-phy siological Relations in the Spermophyte Shoot. 145 
representation which appears in the ‘ Vorlesungen ’, Fig. 305, and is 
here reproduced, although no actual statement to this effect occurs in 
the text. The leaf-primordium is here depicted as arising from a single 
horizontal cell layer, which undergoes division and growth in such a 
D A 
Fig. 24. Diagram to illustrate the mode in which leaves are developed from the growing- 
point of a Phanerogam (reproduced from Sachs’s ‘ Vorlesungen ’, Fig. 305, p. 569). 
manner that the resulting tissue extends downwards for some distance below 
the axil, in a manner entirely in accord with the view put forward in the 
present account. 
3. Comparison of the Leaf-skin Theory with the 
Conceptions of other Writers. 
That what in ordinary parlance we term the 4 stem ’ is wholly or 
in part ‘ foliar ’ in nature is no new idea. It has existed in one form 
and another since a very early date in the history of Botany. In 1841 — to 
go no farther back — Gaudichaud 1 maintained that the unit of which 
a higher plant was built up consisted of (1) a downwardly developed 
system, the root (suppressed, as a rule, except in the embryo), and (2) an 
upwardly developed system distinguishable into (a) a tigellar, ( b ) a petiolar, 
and (c) a laminar region, the two systems constituting a ‘ phyton a series 
of 4 phytons ’ making up the individual. Thus the stem as a plant member 
sui generis and distinct from a leaf was not recognized by Gaudichaud. By 
Hofmeister and Nageli, on the other hand, the shoot was conceived as 
consisting of an axis on which were borne members of another order — 
the leaves. This axis, according to Hofmeister, 2 was not identical 
with the stem, but with its central region only. The outer tissue enveloping 
this core he held to be formed from the leaf-bases, through multiplication and 
1 Mem. de l’Acad. des Sciences, Paris, 1841. 2 Vergl. Untersuchungen, 1851. 
