SELAGINELLA: ALTERATION OF GENERATIONS, 31 
the second place, in the development of its life history it shows, in 
a far higher degree than any other Cryptogam, the connection 
between Cryptogams and Phanerogams. The family is moss-like 
in appearance, mostly European, and belongs to the order Lycopo- 
diacez, the name Selaginella (lesser Alpine Club moss) being a 
diminutive of Selago, the Lycopodium. 
Only one species, Se/aginella selaginoides, is found in England, 
on boggy ground, especially by the sides of small streams and 
ditches, and on wet rocks in mountainous districts. 
Many of the foreign species are known in greenhouses, where 
they are cultivated for their bright metallic green colour. 
The stems are dichotomously branched, and show in a very 
distinct manner what is absent in the Mosses and Hepatics, but 
present in the Ferns, Equisetums, and Lycopods: the fibro-vascular 
bundles. 
These bundles are connected with the cortex by a very loose 
spongy tissue, so that they appear to lie isolated in a cylinder filled 
with air, and connected with the walls only here and there by 
parenchymatous cells. 
The structure of the vascular bundle itself is always uniform. 
The woody portion, or xylem, consists of wider vascular cells in its 
inner, and of narrower vascular cells in its outer part ; the less 
solid portion, the bust or phloém possesses vessels, fibres, and 
parenchymatous tissue. The axial vascular bundle sends out 
ramifications into the branches and leaves. 
The leaves are ligulate, placed in four rows, and are of different 
sizes ; the lateral rows consisting of larger, the upper and under of 
smaller leaves. 
This is a very marked feature, and enables us at once to separate 
it from Fissidens or Hypnum, two genera of mosses which it closely 
resembles. 
Only one kind of spore is produced in Mosses, Ferns, Equise- 
tums, and Lycopods, but in Selaginella, Pillularia, and also in 
Isoéteze, a family of aquatic plants, which is the only one known 
among Cryptogams, in which the stem permanently increases in 
thickness, two kinds of sporangia are produced, Macrosporangia, 
in which are formed four large macrospores, and are found in the 
axils of the lower leaves. Microsporangia, in which a greater 
number of much smaller spores, the microspores, are developed, 
and are found only in the axils of the upper leaves. 
The microspores are the Antheridia, and break up into a small 
number of cells, one of which remains unproductive, and may be 
regarded as an abortive pro-embryo, while antherozoids are 
developed in the remainder. 
The macrospores, on the other hand, produce a pro-embryo 
or prothallium, which bears archegonia, opgping outwardly, 
