III.—BOTANY.
Art. XLIII.—On the Fresh-water Algæ of New Zealand.
By W. I. Spencer, M.R.C.S. England.
[Read before the Hawke's Bay Philosophical Institute, 11th July, 1881.]
Plate XXIII.
Reference to Sir J. Hooker's "Handbook of the New Zealand Flora," pp. 645–646, will show how little attention has in this country been hitherto bestowed upon one of the most beautiful orders of the vegetable kingdom. And as one reads in paragraph after paragraph, in which the various tribes of the fresh-water Algæ are enumerated, such statements as "Very numerous, not hitherto collected in New Zealand"—"This beautiful fresh-water group has not hitherto been collected in New Zealand"—and again, "The species are very numerous and have never been collected or studied in New Zealand," one cannot help feeling that the reiteration suggests to the naturalists of this colony a powerful incentive to undertake the systematic study of this most remarkable and interesting order of plants.
It is with much diffidence that I lay this paper before you to-night, because I feel that I am treading upon unbroken ground, and that the subject is a vast one, involving for its complete investigation much study and much time, neither of which I have been able to devote to it, and also the consultation and comparison of many books which have not been at my command. Nevertheless, if my imperfect attempt has the result of drawing the attention of some of the many able naturalists in this country to a hitherto neglected section of its natural history, and of enlisting other and more competent workers than myself in its investigation, I shall feel that the object I proposed in drawing up this paper has been fully accomplished.
The fresh-water Algae comprise a large proportion of the Chlorospermeæ or Confervoideæ; the number of green Algae which are inhabitants of sea water being comparatively small. They are to be found on damp ground, under the drippings of water, in ponds, streams, waterfalls, even in hot springs where the water has a nearly boiling temperature. They form a green scum on walls, on the bark of trees, and on stones in damp weather—in fact, given the one condition of fresh water moisture, they are almost ubiquitous. Many are plainly visible to the naked eye, and may be seen floating in water, either as scum, as compact green or purple masses, as skeins of threads attached to stones, sticks, or water plants, or as a simple discolora-
