NATURALISTS’ FIELD CLUB

Evening Star, Issue 19844, 18 April 1928, Page 2

NATURALISTS’ FIELD CLUB

INDOOR METING Owing to Urn wot weather being nnfavournble for the work set down—namely, the study in the evening of glowworms and treading for moths along the bush track at, Morrison's Creek—the outing of Saturday last was postponed to a later date. At the indoor meeting held on Monday evening there, was a very good attendance to hear Hr J. K. Holloway’s address, on ‘Freshwater Algae.’ Dr Holloway stated that algae (to which order seaweeds belong) occur in vast numbers all over tho world; but. as his purpose that evening was to deal chiefly with such algae as occur around Dunedin, ho would endeavour, by means of black-board diagrams, notes, and lantern slides, to make known to his hearers a few of the more common species which may be met with almost anywhere in damp places in the open. Algae are divided into three main groups, according to their colors—usually green, red, and brown. In the classification of flowers, for instance. colour does not count; but in algae colour goes with structural features, and so has a scientific significance. Fresh-wator algae, with which Dr Holloway dealt chiefly, are mostly microscopic and unicellular- —viz., each individual plant having but one cell. The fact that they occur in colonies and are surrounded by mucilage renders them not inconspicuous, and they may bo found quite commonly in ponds, reservoirs, wet bush tracks, or on trickling rocks.

Of the bluc-grocn algae (the color of which is due to the blue-green pigment in the cells, in addition to the usual green elilorophyl which all plants have) one of the commonest is Nostoc. Colonies of these take a. curious little form resembling a necklace; others occur in grape-like colonies all over certain places everywhere—on wet rocks or in wet places among sand dunes. At Tomahawk or Pnrakanui, for instance, they could easily bo gathered up in great quantities. Another species (Anabaenn) is much the same as Nostoc, only it is isolated instead of in groups. It is also found on trickling rocks. Other swimming forms were described and illustrated by Ibc lecturer, and special mention was made ol one species —namely, Volvox—the structure of the cells of which is so symmetrical that the lenses of microscopes are sometimes set by it. This particular species docs not occur in Dunedin, though it may be found at Middlcmarcb and other parts of Otago. A hearty vote of thanks was passed to Dr Holloway for his address, and an interesting discussion regarding the fresh-water algae, which frequent local water races, reservoirs, etc., followed. In more tropical countries they become a menace to the water supply, and even bore it is found necessary to check the growth in order to maintain the purity of our water supply.