In an adult in a condition of repose, respiration takes place about eighteen times a minute, in the infant it is more frequent As is well known, it becomes very active under the influence of bodily exertion, or under excitement from any cause whether physical or moral. When, on the other hand, the attention is fixed on a laborious effort, the breath is held so that it very soon becomes necessary to take long and deep inspirations to compensate for the insufficiency of those which preceded. This result of hard work or great strain of mind should be guarded against in children, as their constitution suffers greatly under the influence of incomplete respiration.