The other factors besides allergy in asthma can be divided into two groups. In one are the physiologic changes that go with the bronchospasm itself— emphysema, eosinophilia and polypoid nasal sinusitis. Disturbances in the body water and in the electrolyte balances may be found: the circulation may be abnormal. All these are both interesting and important, but they are parts of the general pathologic picture: they are results of the underlying process and are not concerned directly with the cause of the symptom asthma. They will not be discussed in this paper. In the other group are factors concerned directly with the etiologic basis of the disease and with its treatment. The classification of asthma which was published by me in 19471has stood the test of time. It was, and it still is, helpful in the clinic (see table). The accompanying important point is the age at onset.