INTRODUCTORY COLLECTION. 
33 
Liverworts. Except in the lower forms of these, a main axis, 
or stem and leaves borne upon it, can be distinguished. 
In the third group, or Pteridophytes, including Ferns and 
their allies, which occupy the right-hand wall- case, the plant 
body shows a marked distinction into a stem or ascending axis 
bearing leaves, and a root or descending axis. They are also 
called Vascular Cryptogams, as they contain systems of vessels 
forming bundles of wood and bast, not found in the two other 
groups, which are therefore known as Cellular Cryptogams. 
In the middle of this bay is placed a section of a very large Section of 
Wellingtonia or " Big Tree " {Sequoia gigantea), which was cut large Se ^ uoia ' 
down in 1892 near Fresno, in California. It is about fifteen 
feet in diameter, and perfectly sound to the centre, showing 
distinctly 1,335 rings of annual growth, which afford exact 
evidence of the age of the tree. An instantaneous photograph, 
taken while the tree was being felled, is placed near it, and shows 
its general appearance when living. It height was 276 feet. 
The last two bays are devoted to the great group of Phanerogams 
or seed-plants, where, besides the distinction of stem, leaf, and 
root, and the development of vascular tissue, we find a structure 
unknown in the Cryptogams, viz., the seed, where the embryo, 
or commencement of a new individual, is developed within and 
protected by one or more envelopes (seed-coats), consisting of 
tissues of the mother plant. 
The left-hand portion of Bay IX. contains specimens of the Gymnosperms 
smaller division of seed-plants, the Gymnosperms, in which the cotyledons, 
pollen falls directly on the naked ovule. In the wall-case the Ba y Ix * 
upper row of specimens illustrates the form of the leaf, while 
the lower deals with the stem and root. The internal structure 
of these is demonstrated by means of large sections. Important 
details in structure form the subject of the drawings in the 
upper part of the case. In the left-hand side of the central case 
are specimens of the flower and fruit. The Cycads are of 
special interest, demonstrating the leaf nature of the carpel or 
ovule-bearing organ. 
Passing to the right-hand portion of the bay, we come to the 
angiospermous division of seed-plants, in which the pollen 
penetrates the stigma and fertilises the ovule in a closed 
chamber or ovary, which develops into the fruit enclosing the 
D 
