(46) 



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 of 

 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 



