(224 ) 
matophytes largely predominates; namely, the angio- 
sperms, covered-seeded plants in which the seed is borne 
in a seed-case. These plants also existed in the later 
geological ages, and now form the most important and 
conspicuous part of the vegetation of the earth. The 
covered-seeded plants (cases 59 to 128) fall into two divi- 
sions, the one in which the embryo has a single leaf, the 
monocotyledons (cases 59 to 71); the other in which the 
embryo has two leaves, the dicotyledons (cases 72 to 128). 
(b) Microscope Exhibit. The exhibition microscopes 
occupy small stands in the west wing of the second floor. 
In front of the windows on the right as one enters the wing 
are shown a few of the simplest and smallest forms of plant 
life. Under the lenses of the first microscope are repre- 
sentatives of the diatoms—one-celled organisms, some o 
which have the power of animal-like locomotion; the 
living substance of each cell is enclosed and protected by a 
hard transparent glassy wall consisting of two halves, 
one of which fits into the other like a band-box into its 
cover. The second microscope shows attractive and 
varied forms of fossil diatoms from California. Following 
this are shown ‘‘sea mosses,” or “‘seaweeds,” as they are 
commonly known, and closely related minute plants which 
inhabit fresh water and belong to groups often referred to 
in popular speech as “‘pond-scums” or ooze.” In the 
natural unmagnified condition, many plants of this sort 
seem quite the reverse of attractive, but when placed under 
a sufficiently powerful microscope many of them reveal a 
rare beauty. The ‘“‘sea mosses,”’ or “‘seaweeds,” gradually 
lose much of their natural beauty of coloration on pro- 
longed exposure to the light, but the prevailing elegance 
and symmetry of form and structure persist. 
Following the plants of the seaweed type are several 
representatives of the smaller fungi. The first of these 
specimens illustrates the resting spores of the parasitic 
fungus that causes the well-known rust of rose leaves. 
The second shows a vertical section through the cluster-cup 
