OTAGO INSTITUTE

Otago Witness, Issue 3148, 15 July 1914, Page 76

OTAGO INSTITUTE

MONTHLY MEETING. SEVERAL PAPERS. The monthly meeting of the Otago Institute was held on the 7th, Dr Malcolm i .residing over a good attendance. HOW A MUSCLE WOKKS. Dr Malcolm delivered an address on “ k|pw a Muscle works.” Muscle, he said, was simply meat. Each muscle was a distinct organ, enclosed in a membrane and attached to a particular point. By a contraction of a muscle the movable point was caused to move, and that was how bodily’ motion was brought about. Tne speaker produced legs of a frog, cut from the animal 20 minutes before, and used them as a basis of his experiment. ■ Every muscular contraction, he said, was caused by a nerve stimulus, emanating from a brain cell. In life, these stimuli were produced in the ordinary way. But after death the muscle could be caused to contract by such a stimulus as an electrical current. Dr Malcolm produced an elaborate, yet easily understood, piece of apparatus. The muscle of the frog was stretched between two conducting wires, and attached to one of the wires was an index, by which any contraction or relaxation of the muscle could be registered. He then sent an electric current through the muscle, and the oscillation of the index showed a contraction, and subsequent relaxation had taken place. The oscillation of the mdex was increased by its motion over a sphere covered with lamp black, upon which it traced a pattern corresponding to its movement. The speaker showed how, by comparison with the ascertained vibration of a tuning fork similarly traced on the sphere, the amount of time occupied by the contraction could be measured. He also showed the work or tho muscle in lifting a suitable jveight, when operated upon by an electrical stimulus, and illustrated the failure of the fatigued muscle to respond. Compound or sustained muscular contractions were attributed by Dr Malcolm to a discontinuous series of nervous impulses, and the name given to them, he said, was tetanus. He graphically illustrated the action in this case by means of his carboncovered sphere.

DUNEDIN WEATHEH. Mr' D. Tannobk asserted that Dunedin weather was not the worst in New Zealand, as is so often said. He claimed a very good climate for the city, and quoted figures in support of its contention. It was, the speaker said, the mean minimum temperature at which a plant was able to live that determined whether or not it was hardy. It was found in Dunedin that, owing to the high minimum temperature, gardeners were able to grow a considerable number of plants - that could not be grown in the other centres. The speaker had had no difficulty in growing the North Island native plants, and had grown the Nikau palm, tor instance, in the open air. Reverting to figures, he said that, in Auckland during the year with which he was dealing, 37.04 inches fell on 181 days; in Wellington, 49.29 inches fell on 213 days; in Christchurch. 25.12 inches fell on 138 days; in Dunedin, 42.26 inches fell on 170 days; and, in Invercargill, 48.82 indies fell on 213 days. Christchurch had • the lowest rainfall, Auckland the second lowest, and Dunedin the third, seven inches less Ihan Wellington. Dunedin was second lowest with regard to the number of days on which rain fell. “We have, therefore,” the speaker concluded, ‘‘comparatively pleasant weather in Dunedin.” Dr Marshall remarked that in four years out of every five, it would be found that the hottest day in Dunedin was hotter than the hottest day - in Auckland, though Auckland had more hot days in the aggregate. OTHER PAPERS. Mr_G. Howes showed a; number of aluminium casts of flowers and leaves, and described them interestingly. Professor Benham delivered an interest-, ing address on the native, and other rats, and described the origin of the English rat and its introduction into New Zealand. He also laid on the table papers on the Oligochaeta and the littoral Polychaeta, from the Kermadccs. Dr Benham announced that in September a meeting would he held of a branch of the British Association for the Advancement ■of Science. A certain number of scientists would be the guests of the dominion. They would be at Auckland, and would hold scientific meetings at Wellington and Christchurch. It was hoped that some of them would come to Dunedin, and deliver popular lectures, and that Dunedinites would be able to welcome them. Papers on scientific subjects would be read at the meetings in the north, and persons wishing to have their papers read should communicate, with the secretaries of the various sections upon which papers would be acceptable. The next meeting of the institute will be on August 4.