It was recognized that the pacemaker located at the head of the sino-atrial node had the earliest excitation and controled the heart. Experimental studies indicated the possibility of cardiac impulse arising at lower part of the sino-atrial node or other lower center of automaticity, when physiological pacemaking function at the head of this node is depressed or lost by some influences. The author attempted to prove experimentally the shift of pacemaker, especially in the sino-atrial node by ligation of the atrial artery, vagal stimulation and application of drugs acting on the autonomic nerves. The results are reported with discussion in the present paper.

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It would be extreme importance for the phonocardiographic analysis of murmur in cases of patent ductus arteriosus, to have precise consideration on the size of the ductus. The author has observed the fact that variation of the size of the ductus results in the variation of the pressure gradient between systemic and pulmonary pressure causing significant change in phonocardiographic findings, The role of the size of the ductus arteriosus playing the pathogenic mechanism of pulmonary hypertension in this disease has been also discussed.

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Estimation of plasma renin was made under the various clinical conditions. Plasma renin was increased in patients with malignant hypertension, unilateral renal artery stenosis, nephrotic syndrome and liver cirrhosis with ascites, and in subjects on salt depletion. This conditions are known to be associated with an increase of aldosterone secretion. Thus, present study supports the hypothesis that the renin-angiotensin system mediates aldosterone secretion. Plasma renin was also evaluated in toxemic pregnant women and found to be elevated. A constant increase of plasma renin in malignant hypertension indicates that the kidney plays an important role in the development and the maintenance of high blood pressure. In this disease, however, the basal secretion of renin was decreased on salt depletion, in contrast to normotension and benign hypertension. From this result, it may be assumed that some different mechanism of renin secretion would exist between malignant hypertension and other cases.

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Many studies have been reported in connection with the Korotkoff Sound, the sounds heard over the brachial artery at the time of blood pressure measurement by cuff method, which correspond to so-called Swan's 5 sounds. I have studied the relationship between this sound and hemodynamics status of systemic arterial circulation. Materials studied are divided into 4 groups, namely, 1) 26 cases of arteriosclerosis with systolic hypertension of more than 150 mmHg, 2) 16 cases of arteriosclerosis with systolic pressure of less than 150 mmHg, 3) 7 cases of juvenile hypertension with systolic pressure of more than 150 mmHg, and 4) 20 healthy medical student volunteers. All studies were done at resting status in supine position and the pressure cuff was placed on the right arm in the usual manner for blood pressure measuring. Crystal microphone head was placed hermetically on the brachial artery distal to the cuff, and thus, Korotkoff Sound was recorded. On the other hand, the pick-up of the condenser microphone was placed on the left brachial artery correspondingly to the crystal micro-phone head in the other side, and the arterial pressure pulse wave was recorded. Simultaneously, 11 lead ECG was also recorded. 7 out of 20 normal controls were given L-noradrenaline intramuscularly after the recording, and the effects of this procedure was studied by repeating the recording 5 minutes later. In accordance with previous observations, the pulse wave conduction velocity was greater in the arteriosclerotic group. The 1st-point sounds of Korotkoff Sound were produced near the peak of the percussion wave in all cases. Both the time duration between the peak of R in ECG and the Korotkoff Sound (R-P time), and between the foot of the upstroke of the percussion wave and the Korotkoff Sound (A-P time) were reversely proportional to the systolic blood pressure, at the pressures corresponding to so-called Swan' 1 and 2 points. R-P and A-P times were about the same in both hypertensive and normotensive groups at the pressures corresponding to the Swans' 3, 4 and 5 points. In 7 normal groups, who were given L-noradrenaline subsequent to the control observation, have shown the tendency to increase the R-P and A-P times 5 minutes after the injection. Thus, as the cuff pressure was lowered and the blood flow increased, the production of the Korotkoff Sound gradually approached the foot of the upstroke of the percussion wave and the peak of R in ECG. From this I can infer that the hemodynamics status of systemic arterial circulation, for example, propagation of percussion wave and ECG, and the production of the Korotkoff Sound are closely related with each other. There arise a time difference for the blood flow to reach the narrowed portion of the artery under the cuff, which can be considered the origin point of the Korotkoff Sound. This is quite easily explained by Bernoulli's theory.

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There have been many studies on the correlation between histological changes of the lung an, d clinical findings or cardiopulmonary dynamics in mitral stenosis. However, there are still different opinions as to this correlation. In this presentation the relation between pulmo-nary circulatory disturbances and histological or electron-microscopical findings in patient with mitral stenosis was investigated. Material The investigation was made of 12 patients with mitral stenosis. All patients were submitted to surgical treatment (commissurotomy). Cardio-pulmonary function tests were performed prior to the operation except one. The lung from a patient with mild tuberculosis was investigated for comparison. Methods Small piece of the lung was excised form the lingual region of the left lung at commissurotomy. The specimen was immediately divided into two parts, and a part of them was fixed by infusion using I per cent osmic acid for electron microscopic examination, the other part was fixed with 10 per cent formaldehyde for histological examination. Histological preparations were made in usual fashion, and hematoxylin-eosin, PAS, van Gieson's and Verhoeff's procedures were employed for tissue staining. The fixed specimen for electron-microscopic examination was embedded into methacrylate after preliminary washing with water and following dehydration. And then submitted to ultra-microtome. The slices thus obtained were mounted on a formvar coated mesh for electronmicroscopic observations and photogram. Results (1) It was found histologically that the changes in lung tissue progressed in the order of dilatation of capillaries, thickening of capillary wall and then thickening of alveolar wall. Thickening of alveolar wall was seen in 7 of 12 cases. Moderate to advanced thickening of alveolar wall was accompanied with fibrosis, and the more thickening advanced, the more fibrotic changes became remarkable. Decrease in number of capillaries was predominant and cuboidalization of the alveolar wall was noted in such cases.

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