Certain types of both cardiac and renal disease are attended with disturbances in respiration which occasion unpleasant manifestations. Sometimes the conditions of the heart and kidneys are believed to contribute jointly to the difficulty that may arise. The occurrence of Cheyne-Stokes breathing in uremia has been attributed to cardiac failure which is undoubtedly one of the common causes of such dyspnea; but the labored breathing at times attending renal disease may be independent of the heart in its origin. There is urgent need to-day of a clearer understanding of the immediate physiologic and pathologic conditions which underlie dyspnea, instead of the vague charges against the different organs which are more indirectly involved in the transaction.
The questions to be solved concern the nature or size of the stimulus to rapid respiration. The well-established view that the exciting stimulus to the respiratory center is the carbon dioxid content of the blood