620 DR R. K1DSTON AND PROF. W. H. LANG ON OLD RED SANDSTONE PLANTS 
Zealand species, the life-history of which has been described by Holloway,* 
attains a much larger size before a stem-apex is differentiated. “ This protocorm- 
ous rhizome plays a much larger and more important part than does the simple 
protocorm of L. cernuum. It constitutes the plant body for a whole season and 
may even branch. It appears also that in both L. laterale and L. ramulosum 
it is able to reproduce itself vegetatively.” t The vascular bundles of the more 
or less numerous protophylls borne on the protocorms of these three species of 
Lycopodium end blindly below in the parenchymatous tissue, the protocorm itself 
having no vascular system. 
The protocorm of Phylloglossum, which in the embryo plant resembles that of 
L. cernuum, appears to be repeated as the specialised resting tuber by means of 
which this plant perennates. This region in Phylloglossum can be regarded as both 
primitive and specialised. 
The rootless plant of Horned appears to retain in the adult condition an organisa- 
tion comparable to the protocorm stage in the species of Lycopodium mentioned 
above. The relation of the aerial stems of Hornea to the rhizome is similar to that 
of the protophylls to the protocorm in Lycopodium. 
The resemblance of the protocormous rhizome of the ancient Vascular Cryptogam 
Hornea to the protocorm present as a transient embryonic phase in some existing 
species of Lycopodium supports the suggestion made by Treub as to the nature 
of the protocorm. He was led to assume “ que chez les ancetres des crypto- 
games vasculaires actuels un organe a pris naissance qui a du avoir beaucoup de 
ressemblance avec le tubercule embryonnaire des Lycopodes.” His discussion is 
summed up thus : — 
“ Le tubercule embryonnaire chez les Lycopodes est un organe rudimentaire.” 
“ L’organe admis theoriquement chez les ancetres des Cryptogames vasculaires 
actuels, et designe ci-dessus comme ‘ predecesseur de la pousse feuilMe telle quelle 
se presente maintenant chez les plantes vasculaires ’ existe encore aujourd’hui 
a l’etat passager, dans le genre Lycopodium. Cet organe nest autre que le 
tubercule embryonnaire .” 
“ Aussi je propose de donner au tubercule embryonnaire des Lycopodes le nom 
de protocorme .” | 
In view of the morphology of Hornea it may be said that the existence of this 
organ does not require to be theoretically assumed in archaic Vascular Cryptogams, 
but is demonstrated. 
So far as the anatomical construction of the Rhyniacese is concerned, we can only 
recognise its simplicity and its direct relation to the primary vegetative functions 
of land plants, absorption, conduction, aeration, and protection. It is only necessary 
* Holloway, Trans. New Zealand Institute, vol. xlviii, 1915, pp. 253-303. 
t Ibid., vol. xlix, 1916, p. 90. 
t Treub, Annales du Jardin Bot. Buitenr.org , vol. viii, 1890, p. 30. 
