(112) 



The Thallophyta (cases I to 40), may be defined as 

 plants without true roots, stems, or leaves; but notwith- 

 standing their simple structure they exhibit an infinite 

 variety of form and color. 



The Myxomycetes or slime-moulds (case 1), standing 

 at the bottom of the plant-scale, occupy the first exhibition 

 case placed at the right hand side of the stairway from 

 the main floor. They are thallophytes, having neither 

 chlorophyl nor (in their vegetative condition) a cell-wall. 

 These very simply constituted plants usually grow upon 

 and derive their nourishment from decaying organic sub- 

 stances. They vary greatly in size, some being exceedingly 

 minute, others assuming the form of relatively large ir- 

 regularly shaped masses spreading in all directions as they 

 grow. Most of the plants are small, and the structure is 

 very delicate, in fact some are so fragile that a mere breath 

 of air will ruin them. 



Following the slime-moulds stand the cases devoted to 

 the algae or seaweeds (cases 2 to 16), which may be briefly 

 defined as thallophytes with chlorophyl, the green coloring 

 matter of plants. The plants of this series are much more 

 variable in form than those of the preceding, and are also 

 much more numerous. Some forms are microscopic, 

 others attain considerable size. The first case of the series 

 is occupied by representatives of the blue-green algae 

 (case 2) and the diatoms. The plants of these two groups 

 are minute, so much so that in most cases the individuals 

 can be well seen only with the aid of a microscope. As one 

 finds them in nature they commonly form slimy or oozy 

 masses which are not particularly attractive to the naked 

 eye, but under a compound microscope they are of very 

 great interest. Following the series just mentioned are the 

 green seaweeds (cases 3 and 4), the group which includes the 

 plants that are sometimes called the pond-scums, green 

 slimes, green felts, and stoneworts. Some of these are 

 microscopic; however, some of the green seaweeds attain a 

 considerable size and begin to look a little more like what 



