228 Barratt. — A Contribution to our Knowledge of the 
internode below is marked by a considerable development of metaxylem at 
this point. This has been interpreted by Browne as affording indications 
of the presence of a node. According to Vidal’s (6) conception of the 
vegetative axis of Equisetum as being made up of a series of segments each 
composed of a node with an inferior internode, the fact that there is an 
undoubted internode immediately below the insertion of the annulus would 
presuppose the existence of a node above. On the other hand, there are 
certain facts which negative such a view ; these are (i) the course of the 
protoxylem strands, (2) the total absence of vascular supply to the annulus. 
The protoxylem strands from the internode pass without any disjunction to 
the level at which the first sporangiophore traces arise, and hence there is 
no alternation at the so-called ‘ node ’. There may be apparent forking of 
the strands, but this is due to the fact that the protoxylem strands in the 
bundles of the internode below are often double, which, separating as they 
enter the cone, produce this appearance of forking. This appearance is 
emphasized by the disposition of the metaxylem at this region, which is 
similar to that at the so-called nodes from which the sporangiophore traces 
arise. 
The absence of vascular tissue in the annulus has been frequently 
noted. In itself this is not an insuperable objection to the foliar theory 
because the ochreola which occurs at the base of all branches always lacks 
traces. 
In this connexion it is interesting to consider certain abnormal annuli 
found among the material used in this investigation. Fertile annuli with 
well-developed sporangia were found in both E.palustre and E . sylvaticum. 
They varied in form ; some were fully peltate (PI. VI, Fig. 3), others bore 
sporangia only on the upper surface. Not one of the structures, however, 
possessed any trace of a vascular system. 
On the whole, therefore, though the vascular structure does not support 
the view of the foliar nature of the annulus, it cannot be said to throw much 
light on the morphology of this organ. 
Discussion and Summary. 
In order to arrive at a true conception of the vascular structure of 
Equisetum it is necessary to look at the plant as a whole. Any general 
explanation or theory put forward must be capable of embracing characters 
found in all the organs of all the species. 
It very often happens that a study of the structure of the early stages 
of the individual throws light on the phylogenetic history of the genus. 
Jeffrey (4), in his account of the sporeling of E. hiemale , describes the 
vascular system at the base of the first shoot as siphonostelic, but it is clear 
from a study of sporelings of E. arvense and E. maximum , that the vascular 
cylinder at' the' base of the first sho'ot in -these species is protostelic. This 
