More forms were found, but could not be determined by me. This list will give an idea of the variety of forms to be met with in the hunt for ague plants; still, they are as well marked in their physical characters as a potato is among the objects of nature. Although I know you are perfectly familiar with algae, still, to make my report more complete, in case you should see fit to have it pass out of your hands to others, allow me to give a short account of the Order Three of Algae, namely, the Chlorosporeae or Confervoid Algae, derived from the Micrographic Dictionary, this being an accessible authority.
Algae form a class of the thallophytes or cellular plants in which the physiological functions of the plant are delegated most completely to the individual cell. That is to say, the marked difference of purpose seen in the leaves, stamens, seeds, etc., of the phanerogams or flowering plants is absent here, and the structures carrying on the operations of nutrition and those of reproduction are so commingled, conjoined, and in some cases identified, that a knowledge of the microscopic anatomy is indispensable even to the roughest conception of the natural history of these plants; besides, we find these plants so simple that we can see through and through them while living in a natural condition, and by means of the microscope penetrate to mysteries of organism, either altogether inaccessible, or only to be attained by disturbing and destructive dissection, in the so called higher forms of vegetation. We say "so-called" advisedly, for in the Algae are included the largest forms of plant life.
The Macrocystis pyrifera, an Algae, is the largest of all known plants. It is a sea weed that floats free and unattached in the ocean. Covers the area of two square miles, and is 300 feet in depth (Reinsch). At the same time its structure on examination shows it to belong to the same class of plants as the minute palmellae which we have been studying. Algae are found everywhere in streams, ditches, ponds, even the smallest accumulations of water standing for any time in the open air, and commonly on walls or the ground, in all permanently damp situations. They are peculiarly interesting in regard to morphological conditions alone, as their great variety of conditions of organization are all variations, as it were, on the theme of the simple vegetable cell produced by change of form, number, and arrangement.
The Algae comprehend a vast variety of plants, exhibiting a wonderful multiplicity of forms, colors, sizes, and degrees of complexity of structure, but algologists consider them to belong to three orders: 1. Red spored Algae, called Rhodosporeae or florideae. 2. The dark or black spored Algae, or Melanosporeae or Fucoideae. 3. The green spored Algae, or Chlorosporeae or Confervoideae. The first two classes embrace the sea-weeds. The third class, marine and aquatic plants, most of which when viewed singly are microscopic. Of course some naturalists do not agree to these views. It is with order three, Confervoideae, that we are interested. These are plants growing in sea or fresh water, or on damp surfaces, with a filamentous, or more rarely a leaf-like pulverulent or gelatinous thallus; the last two forms essentially microscopic. Consisting frequently of definitely arranged groups of distinct cells, either of ordinary structure or with their membrane silicified--Diatomaceae. We note three forms of fructification: 1. Resting spores produced after fertilization either by conjugation or impregnation. 2. Spermatozoids. 3. Zeospores; 2, 4, or multiciliated active automobile cells--gonidia--discharged from the mother cells or plants without impregnation, and germinating directly.
There is also another increase by cell division.