of the Anatomy of the Genus Selaginetla , Spr. 139 
Ophioglosseen.’ The ground-tissue is sharply marked off 
from the vascular system, but a true endodermis is not 
present. The vascular bundle is, however, slung in a lacuna 
by longer or shorter cuticularized cells, or the space may be 
filled with parenchyma. This trabecular tissue Russow looks 
upon as being the analogue of an endodermis. The cortex is 
composed externally of sclerotic fibres forming a supporting 
ring just beneath the epidermis. 
Hegelmaier (12) discusses the nature and mode of origin of 
the cuticular band on the endodermal cells, pointing out that 
quite close to the growing apex the cuticular ring has not yet 
appeared, the whole wall giving a blue reaction with chloro- 
zinc-iodine. Shortly afterwards, however, the cuticularization 
appears, and the wall in that region gives a brown or violet 
reaction with that reagent. My own observations on the 
mode of origin of this peculiar ring differ somewhat from 
those of Hegelmaier. I have given these in detail in the 
course of my description of S. Martensii . I have found the 
method advocated by Hegelmaier, viz. boiling in caustic 
potash, most useful in isolating the vascular system and 
tracing the courses of the leaf-traces and protoxylem-cords. 
Braun (13) has with justice drawn attention to the existence 
of a third type of leaf in the heterophyllous species, viz. the 
axillary leaf (Achselblatt). The importance of this leaf will 
be seen later in the discussion of the insertion of leaf-traces on 
the steles, more especially in the tristelic species. 
Treub’s developmental researches (14) may be best sum- 
marized in his own words : — ‘ II suit de la description quo je 
viens de donner que les branches du Selaginetla Martensii 
sont les monopodies qui, se ramifiant periodiquement, forment 
deux rangees de membres lateraux, et non des sympodes 
provenant de dichotomies successives.’ He describes in some 
detail the development of the various layers of the stem, 
agreeing with Russow in considering the lacunar tissue as 
belonging to the fundamental tissue-system, an opinion which 
has been confirmed by the more recent researches of Vladescu 
and Strasburger. He differs from Russow in believing that 
