88 TENTH ANNUAL REPORT OV 



gans, and in others the leaves are reduced to scales or spines, while 

 the stem and hranches are expanded and become not merely leaf-like, 

 but actually discharge the functions of leaves. In the reproductive 

 organs or flowers, too, we find equal variety ; from the most elaborate 

 and often gorgeous structures to the simplest and plainest, till at last 

 we arrive at flowers, whose organization is so low that not only have 

 calyx and ct)rolla disappeared, but the very seed-vessel itself is re- 

 duced to an open scale or is wholly absent. Yet in all tliese modifi- 

 cations it is merely the means that are varied ; the end proposed is as 

 efficiently attained by the simplest agency as by the most complex ; as 

 if the Creator had designed to show us plainly how it is the same to 

 Him to act by many or by few, by the most elaborate arrangement 

 when He wills it, and by the simplest when that is His pleasure. 



In all the cases of which we have as yet spoken, seeds are the result 

 of the vegetable cycle ; a seed being a compound body, containing an 

 emhryo or miniature plant, having stem, root, and leaf already organ- 

 ized, and enclosed with proper coverings or seed coats. But some 

 plants do not produce such seeds. At least one-sixth of the vegetable 

 kingdom, perhaps more, are propagated by isolated cells (or spores) 

 cast loose froin the structure of which they had formed a portion, and 

 endowed thenceforth with independent powers of growth and devel- 

 opment. Such are the reproductive bodies of the Ferns, the Mosses, 

 and all plants below them in the vegetable scale, concluding with the 

 large class to which our attention will now be confined — the Alg^e — 

 wliich of all are the lowest and simplest in organisation. 



The framework of every vegetable is built up oi' cells, little mem- 

 branous sacks of various forms, with walls of varying tenacity, empty, 

 or containing fluid or granular, organized matter, from which new 

 cells may be developed. Among more perfect plants there is, in dif- 

 ferent parts of the same individual, considerable variety in the form 

 and substance of the cells ; those of the wood and of the veins of 

 the leaves being different from those of the soft part of the leaves, 

 and these again different from those of the skin which is spread over 

 the whole. But as we descend in the scale of organization, greater 

 and greater uniformity is found. Below the Ferns, no vascular tissne 

 and no proper wood-cells occur ; and at last in the Algje, no cells 

 exist differing from those of ordinary parenchyma or soft cells, such 

 as compose the pulp of a leaf. Alga?, then, together with Mosses, 

 Lichens, and Fui/gi, are termed cellular plants, in contradistinction 

 to Ferns and Flowering jjlants, which are denominated vascular. 

 Among the most perfect of the Algje, however, though the cells are 

 all of the same substance and nature, all parencJdmatic, they are of 

 various forms and arrangement in different portions of the vegetable, 

 often keeping up a very perfect analogy with the double system of 

 arrangement — the vertical and horizontal, or woody and cellular sys- 

 tems — of higher plants. Thus the cells of the axis of the compound 

 cylindrical Alga3 are arranged longitudinally, like the wood-cells of 

 stems, while those of the periphery or outer coating of the same Alga? 

 have a horizontal direction. 



In the most perfect of such Algas the frame still consists of root, 

 stem, and leaves, developed in an order analogous to that of higher 

 plants. Passing from such, we meet with others gradually less and 



