============================================================ Ages | Males |Percentage | Females |Percentage |-----------|Increase or|-----------|Increase or | 1900| 1911| Decrease | 1900| 1911| Decrease ------------+-----+-----+-----------+----------------------- Under 5 | 54.2| 39.8| -26.27 | 45.8| 33.3| -27.29 5-9 | 4.7| 3.4| -27.66 | 4.6| 3.1| -32.61 10-14 | 2.9| 2.4| -17.24 | 3.1| 2.1| -32.26 15-19 | 4.9| 3.7| -24.49 | 4.8| 3.3| -31.25 20-24 | 7.0| 5.3| -24.29 | 6.7| 4.7| -29.85 25-34 | 8.3| 6.7| -19.28 | 8.2| 6.0| -26.83 35-44 | 10.8| 10.4| -3.70 | 9.8| 8.3| -15.31 45-54 | 15.8| 16.1| +1.90 | 14.2| 12.9| -9.15 55-64 | 28.9| 30.9| +6.92 | 25.8| 26.8| +0.78 65-74 | 59.6| 61.6| +3.36 | 53.8| 55.1| +2.42 75 and over|146.1|147.4| +0.89 |139.5|139.2| +0.22 All ages | 17.6| 15.8| -10.23 | 16.5| 14.0| -15.15 ------------------------------------------------------------ [1a] _Monthly Bull., Dept. of Health, City of New York_, III (1913), 113. [1b] Dublin, _Amer. Jour. Public Health_, III (1915), 1262. CHAPTER II SENSITIZATION TO PROTEIN FOODS The first introduction under the skin of a guinea-pig of a minute quantity of egg-white or other apparently harmless protein substance is itself without visible injurious effect, but if this is followed by a second injection of the same substance after an interval of about ten days, the animal will die in a few minutes with symptoms of violent poisoning. Whatever be the physiological explanation of the remarkable change that thus results from the incorporation of foreign protein into the body, there can be no doubt that the phenomenon known as protein sensitization or anaphylaxis is relatively common.[2] Sensitization to proteins came to light in the first instance through the study of therapeutic sera, and has been found to have unexpectedly wide bearings. It is now known that not only the rash and other symptoms which sometimes follow the administration of horse serum containing diphtheria antitoxin, but the reaction to tuberculin and similar accompaniments of bacterial infection, are probably to be explained on the principle of anaphylactic change. The sensitiveness of certain individuals to the pollen of particular plants (hay fever) is also regarded as a typical instance of anaphylaxis, accompanied as it is by asthma and other characteristic manifestations of the anaphylactic condition.