If after the deposition of the drop, a little lycopodium be scattered over the surface, it is seen that a circular space surrounding the drop, of about the size of a shilling, remains bare, and this, however often the dusting be repeated, so long as any of the carbon bisulphide remains.
B, Lycopodium cernuum.
This fact leads to the consideration of Phylloglossum, which resembles the embryo of Lycopodium cernuum in so many respects that it has been spoken of as a permanently embryonic form of Lycopod: it is in some respects the simplest existing Pteridophyte.
Stationary waves are formed in the air in the dust-tube if the length is rightly adjusted by the closely-fitting piston, and the lycopodium dust collects at the nodes in little heaps, the first being at the fixed end and the last just in front of the piston on the sounder.
The sporangia of the Psilotaceae are associated in synangia, which occupy the same position relatively to the sporophyll, as the single sporangium of Lycopodium or the group of sporangia in Spenophyllum majus.
This order contains the two genera Phylloglossum and Lycopodium; the former has a single species, confined to Australia, Tasmania and New Zealand, while nearly one hundred species of Lycopodium are known.
A number of species of Lycopodium are epiphytic and those of Isoetes live submerged in water.
The sporangia agree with those of Lycopodium in structure and position.
The cones, which in some instances at least were heterosporous, presented a general resemblance to those of Lycopodium and Selaginella, a single sporangium being situated on the upper surface of each sporophyll.
The anatomy of Lycopodium presents considerable variety in detail, but the stem is always monostelic and the development of the xylem centripetal, the protoxylems being situated at the periphery of the stele; pericycle and endodermis surround the stele, and the wide cortex may be more or less sclerenchymatous.