120 The Nature of Precipitin Reactions 



months still gave excellent reactions with its antiserum but not with 

 other antisera, a fact independently observed by Uhlenhuth (25, VI. 1901). 



In the same paper I stated that I had preserved antiserum 42 days 

 dried upon filter paper, a fact which has been also noted by Corin, and 

 Stockis (v. 1901) as cited by Ziemke (17, x. 1901, p. 732). These 

 authors have kept dried antisera (globulin) for two months and found 

 it still active. Ziemke states that he kept dried antiserum for three 

 months but found that it had then lost in power. Biondi (1902) has 

 also preserved dried antisera for several months. 



The fact that dried bloods give reactions after the lapse of a 

 considerable time, months or even years, has been fully established by 

 Uhlenhuth, and confirmed by others. It is true nevertheless that the 

 serum becomes insoluble after a time, the length of which appears to 

 vary considerably. It is doubtless for this reason that old dried bloods 

 not infrequently give very feeble reactions. 



Ziemke (1901) obtained negative results with blood stains 25 years 

 old. Biondi (1902) obtained reactions with human blood stains which 

 had been dried 10 15, but not with those dried 20, years; Modica (1901) 

 on the other hand claims to have obtained a reaction with blood 

 dried 25 years. Uhlenhuth (5, vi. and 25, vn. 1901) obtained reactions 

 within 1 minute with bloods dried 6 to 12 years. I found (1901) that 

 blood dried and kept at 37 C. in the dark for 42 days and blood 

 hung for 6 months exposed to the air in the laboratory still gave 

 reactions. Dried blood exposed for 30 minutes to a temperature of 

 100 C. remained unaffected. Ferrai (1901) and also Biondi (1902, p. 30) 

 have found dried blood acted in the way that I have stated. They 

 found however that reactions did not take place after it had been 

 exposed to 130 C. for 1 hour, to 150 for 10 minutes, or to 160 for 

 5 10 minutes. 



Graham-Smith and Sanger (1903, p. 274) have also studied the 

 influence of putrefaction on sera and antisera. 



"Following a suggestion of Dr Nuttall's, in order to determine 

 the influence of specific bacteria on serum, 1 in 21 dilutions in salt 

 solution of ox and horse serum were inoculated with a series of 

 organisms. Undiluted human pleuritic exudate was similarly treated. 

 All were incubated for 5 days at 37 C. and then left at room 

 temperature for 36, 50, and 40 days respectively ; but the horse serum 

 was allowed to undergo natural putrefaction also for the last 10 days. 

 With the exception of the putrefactive bacteria none gave rise to very 

 considerable growth, and in nearly all cases by the time of examination 



