623 A CHLOROFORM FATALITY. to the brain, where their separation occurs. Dr. McKendrick adopted the first theory, while he allowed that it was not, in all probability, a final explanation of the mechanism of the sense of hearing. The lecture was illustrated by models and explanatory photographs, by which the speaker was able to point to the minute structure of the organ of Corti as an indication that it was unlikely that it acted as a whole. Dr. William Snodgrass, Dr. McKendrick's assistant,

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... he said, counted the fibres in the cochlear division of the auditory nerve and had found them to amount to at least 18,000. Certainly such minuteness of anatomical detail would tend to support von Helmholtz's theory. In "Foster's Physiology" this same point-that the minuteness of structure irresistibly suggests that the organ of Corti is an arrangement for analysis of sound as well as for its reception-is made. "We have only to suppose," says Professor Foster, "that of the long series of rods of Corti, varying regularly, as these do, from the bottom to the top of the spiral, in length and in the span of their arch, each pair will vibrate in response to a particular tone, and the whole matter seems explained." He immediately, however, advances among others two reasons why the question should not be considered as at rest. The variation in length of the fibres along the series is insufficient for the work thus assigned to them, and they are wholly absent in birds, which are known to clearly appreciate musical sounds. Dr. McKendrick closed an interesting lecture by showing, on a model constructed by Professor Crum Brown and himself, that the ear was not only able to analyse a compound wave of sound, but also to appreciate wave form-a fact that was pointed out by Lord Kelvin as long ago as 1878. -