The Biological or Precipitin Test for Blood, considered mainly from its medico-legal aspect. II.

Abstract

1. Powerful anti-sera may be produced by the intravenous injection of smaller quantities of serum than have hitherto generally been used (p. 260).2. Nuttall's quantitative method affords a simple and fairly accurate means of determining the quantity of precipitum formed. By its means quantitative differences can be appreciated which are scarcely, or not at all, apparent in the tubes on inspection (p. 263).3. Normal saline solution is the best diluent for normal sera, and 1—21 has been found to be a convenient dilution. Increase of salt has very little effect on the production of precipitum (p. 266).4. The quantity of precipitum formed is not influenced by the temperature at which the experiment is conducted (i.e. between the temperature of the ice-chest and 37° C.) (p. 268).5. In the case of dried bloods time per se does not destroy their capacity for reacting with their homologous anti-sera. Fluid sera appear to deteriorate slightly by keeping (pp. 269—274).6. Putrefaction of the serum, or anti-serum, does not affect the production of a specific precipitum (p. 274).7. Although the intimate mixture of lime and blood completely destroys the latter, the former is not present in sufficient quantity in ordinary earths to affect blood mixed with earth. The presence of small quantities of lime, however, gives rise to a clouding in solution, which can be got rid of by the passage of CO2, and subsequent filtration (pp. 276—281).8. The presence of even small quantities of acids, or alkalis, rapidly reduces the quantity of precipitum formed (pp. 281—284).9. In diseased conditions a marked alteration may occur in the quantity of precipitum (pp. 265 and 285).10. The volatile antiseptics produce little effect on sera, even after long contact, but formalin, corrosive sublimate, lysol, lysoform, the sulphates of copper and iron, and nitrate of silver, especially in strong solutions, exert a very deleterious action (pp. 287 and 358).11. Blood dried on fabrics, and materials in common use (with the exception of certain leathers) may with adequate precautions be readily diagnosed (p. 290).12. After an undiluted anti-serum has been raised to a temperature beyond 60° C. the capacity for producing precipitum is diminished, and it is destroyed completely after exposure to 68° C. These effects seem to be produced at lower temperatures in normal undiluted sera (pp. 354–55).13. The precipitum-producing power of normal sera is reduced by filtration through a Chamberland filter, but not by passage through a Berkefeld filter (as far as the experiment was conducted) (p. 357).