One of the chief causes of death in the valley of the Amazon is lobar pneumonia. This is due in part to the low resistance of the native, a factor which has been discussed in a previous publication.1 In an industrial enterprise such as the Ford rubber plantation, the control of this disease assumes importance second, perhaps, only to the control of malaria and to general sanitation. In the hospital of the company, located at Boa Vista, Rio Tapajóz, Brazil, there was an admirable opportunity to study tropical pneumonia, and therefore I undertook a series of investigations in an effort to understand the disease more fully.
In the course of the investigations I had occasion to make some tests for the fragility of the erythrocytes. I expected, particularly in cases of jaundice, that the resistance of the red blood cells might become less, but instead in many cases it