Effect of Heat on Precipitins 



115 



"Almost quite destroyed." 



t Rabbit treated with human albuminous urine. 



It will be seen froin the above that all observers agree in finding 

 that a temperature of 60" C. does not destroy the efficacy of haematosera. 

 In the absence of detailed observations regarding the effects of tem- 

 perature, Dr Graham-Smith (29, Vii. '03, p. 354) carried out some 

 experiments at my suggestion by means of my quantitative method, his 

 results being as follows : 



" In order to determine quantitatively the effects of heating on the 

 precipitum-forming property, specimens of antisera were heated in 

 small sealed capillary tubes attached to the side of a thermometer in 

 a water-bath. 



Specimens of anti-ox serum were heated for 5 minutes each, and of 

 anti-sheep serum for 1"5 minutes, at the temperatures given in the 

 following table. Subsequently "1 c.c. of each sample was added to b c.c. 

 of a 1 : 21 dilution of its homologous blood, and the resulting precipitum 

 measured quantitatively. 



After the process of heating, no visible change was noticed in the 

 anti-ox serum till a temperature of 65° C. was reached, when the fluid 

 became slightly opalescent. At 70'' C. this opalescence was very marked, 

 and at 75" C. the serum became gray, opaque, and solid. In the case of 



8—2 



