166 THE AGGLUTINJN8. 



the same individual variable from day to day and even from hour to 

 hour, and so far we have no satisfactory explanation of this varia- 

 tion. Compaired with the agglutinating property of the blood, that 

 of the urine is always feeble. This, together with its variability, 

 renders the use of this secretion in place of blood serum impractic- 

 able. Serum obtained by vesication often shows marked agglutinat'- 

 ing power. In the few cases in which the test has been made, bile 

 manifests this reaction in a fairly well marked manner. Often the 

 reaction may be easily and ;plainly obtained with tears. However, 

 this secretion is subject to marked variation in its agglutinating 

 power, and it has been found that tears obtained by artificial stimu- 

 lation are generally devoid of this property. In immunizing animals 

 it has been found that pus obtained from abscesses due to the bacillus 

 of Eberth may show a high degree of agglutinative power. Agglu- 

 tinins may pass from the mother to the fetus and may be transferred 

 from the mother to the child in the milk. The agglutinins seem to 

 be fairly stable bodies, and some of them may be heated to 140° 

 without destruction, but that of the typhoid bacillus is destroyed at a 

 temperature of 115°. Antiseptics, so far as they have been tested 

 seem to be without effect upon the agglutinins. Typhoid serum 

 may be treated with formalin and kept quite indefinitely without loss 

 of its agglutinating property. However, the use of antiseptics is not 

 necessary in order to have a serum retain its agglutinating action. 

 A typhoid serum may be used as a culture medium for the germs of 

 cholera, anthrax, diphtheria, or of the ordinary putrefactive bacteria 

 without diminution of its agglutinating iproperty. Indeed, a highly 

 active serum will retain its agglutinative action after it has been 

 made putrid by bacterial growth. Dilute mineral acids decrease the 

 agglutinating property of typhoid sera, but when the acid has been 

 added in very dilute form and has not remained long in contact with 

 the serum, partial restoration may be induced by neutralization with 

 alkali. Acetic acid has a like, but less marked effect. Caustic 

 alkalis have an action similar to that manifested by acids. Appar- 

 ently the agglutinins are not altered by any of the digestive ferments. 

 Indeed, pepsin seems to protect agglutinins to some extent against 

 the effecte of dilute hydrochloric acid, and trypsin has a similar pro- 

 tective action against dilute alkalis. 



Filtration of blood serum through porcelain removes the agglu- 

 tinins, inasmuch as it has been demonstrated that the filtrate has lost 

 largely or altogether the agglutinating property. Saturation of 

 typhoid serum with magnesium sulphate leads to precipitation of 

 the greater part or all of the agglutinin. If the precipitate be dis- 

 solved in water it will be found that the agglutinin has not been 

 destroyed by the action of this reagent. Half saturation with 

 ammonium sulphate precipitates practically all of the agglutinin ; 

 and complete saturation with cfalorid of sodium has a like effect. It 



