An abattoir investigation into kidney condemnations due to renal cysts in pork pigs from one producer showed a prevalence of 47.5 per cent. Affected pigs were the progeny of a landrace boar. Similar cysts found in a small sample of day-old piglets sired by the same boar indicated a congenital origin. A marked variation in size and frequency of cysts in the kidneys of slaughtered pigs was seen, some resembling the severity of polycystic kidneys. Histologically cysts appeared to be of tubular origin. The prevalence of affected pigs in slaughter groups from the single herd could be genetically determined. If this were so the data would be consistent with autosomal dominant inheritance. A breeding experiment to examine this hypothesis is in progress.

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In patients with myocardial infarction, from 5 to 17 per cent will develop shock which has a mortality rate of from 80 to 90 per cent when untreated.' In these patients, there is a reduced stroke volume accompanied by tachycardia and peripheral vasoconstriction.2 It has been postulated by some that it is the failure of adequate vasoconstriction to compensate for the degree of fall in cardiac output that is the essential problem in shock accompanying myocardial infaretion.3 , 4 However, it was also once thought that the drop in blood pressure after infarction was beneficial.But, Corday and his associates 5 in 1949 showed that, in dogs, there was a loss of contractility and a ballooning of the myocardium in the area of myocardial infarction when hypotension was present. These factors caused a marked diminution in cardiac output. As soon as the blood pressure in the dogs was raised, the ballooning disappeared and the cardiac output increased. These same workers also showed that hypotension in cardiogenic shock caused a marked diminution in coronary blood flow which was overcome when the systemic blood pressure was raised. Nonetheless, the physiologists, such as Aviado have long contended that vasoconstriction per se is not desirable. Thus, it soon becomes evident that the factors involved in shock are not as well understood as we would like, nor is there any unanimity, therefore, on the type of therapy needed. However, it is self-evident that immediate and rapid therapy is necessary to increase cardiac output and coronary blood flow, and thereby to alleviate myocardial hypoxia with diminished myocardial carbohydrate metabolism and reduced cardiac function, while, at the same time to maintain flow to the brain, kidneys and other vital organs.To accomplish these ends, a number of methods have been used including plasma volume expanders, intra-arterial blood or plasma transfusions, extracorporeal circulation' and pressor amines. The last method is the one most readily available for use in every day practice and so, at this time, is of most importance from a practical point of view.