OTAGO INSTITUTE

Evening Star, Issue 15539, 8 July 1914, Page 9

OTAGO INSTITUTE

The monthly meeting of the Otago Institute was held last evening at the Museum. . . , , , , Dr Malcolm presided and delivered the first address—illustrated by expenment —on 1 How a Muscle A\ orks. Many people, he said, had heard of the experiment in which students, by sticking pins into an amxjutated leg, caused tho toes to twitch. The muscles of a cold-blooded animal like the frog remained irritable after death for a longer period than those of a warmblooded animal, and if one were killed by destroying tho brain, the tissues lived for a considerable time. The frog’s muscle, which ho had dissected for*tho evening’s experiments, had been cut out 20 minutes before, and the heart was probably still beating. In life a muscle contracted in response to a nerve impulse passing along it, and after death, as ho would show, it would contract to an external stimulus, tho most satisfactory being an electrical impulse. Ilie muscle ■uitli whieli the doctor experimented was stretched upon an apparatus connected to a small electric battery on the one side and , to a revolving lamp-black sphere, on tho other side. A steel pointer being placed against this sphere, and the current discharged into the muscle, the extent of the muscle s contraction, and also tho period of time between contraction and relaxation, were drawn bv the pointer upon the smeared cylinder. This twitch was called the simple muscle contraction, and by further experiment _ the lecturer showed the effect of fatigue on a muscle, until there was no response at all to the electrical stimulus. An illustration of compound or sustained muscular contractions followed. That is to say, a discontinuous series of stimuli were sent into the muscle so fast that the second stimulus arrived before the contraction was complete, thus preventing relaxation. This condition the lecturer described by the term tetanus. Dr Malcolm proceeded to describe the structure of the muscle, and ho noted that it worked much more economically than a steam engine, working in a ratio of one of work to two of heat produced, which tho bestworking steam engine could not emulate. In tho course of further interesting remarks, he also informed his auditors that every time a muscle worked there was not only a, mechanical change and a chemical change, but also an electrical change. Mr 0. Howes showed a number of

leaves and spiders, and described them interestingly. These were made by Air Clark. Dr Benham delivered an address on the native and other rats, and described the origin of the English rat ami its introduction into New Zealand. The doctor also announced that in September a meeting would be 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 bo 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 lie able to welcome them. Papers on scientific subjects would be read at the meetings in the north, .and persons wishing to hare their papers read should communicate with the secretaries of the various sections upon which papers would be acceptable.