SPECIAL TOXICOLOGICAL TESTS 271 



can be recognized with certainty. A solution of o.ooooi gram 

 of potassium tellurite in lo cc. of mold infested gelatin medium 

 in a cotton plugged test-tube gave out a strong odor of garlic for 

 several weeks. 



Biginelli ascertained that the gases formed by Penicillium 

 hrevicaule in arsenical cultures were completely absorbed by solu- 

 tions of mercuric chloride with the formation of a double compound 

 of mercuric chloride and diethyl arsine which is quite easily decom- 

 posed accompanied by the reappearance of the garlic odor. 



The test is unlimited in its application and will respond in the 

 presence of all manner of organic substances and bacterial contami- 

 nations. It is far more delicate than any of the chemical tests and 

 can be carried out in much shorter time. 



Toxicity Tests with Defibrinated Blood. — The older physi- 

 ologists and toxicologistsmade the interesting observation that toxic 

 substances of various kinds produced certain changes in the blood. 

 Some poisons disintegrated the red corpuscles, some caused the 

 corpuscles to clump or to agglutinate and still others reduced or 

 even completely inhibited the coagulating power of the blood. 

 These phenomena have suggested the possibility of estimating or 

 measuring the toxicity of certain groups or classes of substances by 

 noting the effects which they produce when brought in contact 

 with red blood corpuscles. The more important groups of toxic 

 substances which give rise to marked reactions with red blood 

 corpuscles are the toxalbumins or toxins, the saponins and many of 

 the toxic chemical compounds. The following tests may prove of 

 value in the food and drugs laboratories. 



Toxalbumins or Toxins. — Toxalbumins and toxins are poisonous 

 substances formed in plants and animals as the result of microbic 

 invasion and also as the result of metabolism in the plant or animal 

 itself. Of special interest are the vegetable toxalbumins which 

 possess the remarkable property of clumping, agglutinating and 

 finally precipitating red blood corpuscles and have therefore been 

 designated "vegetable agglutinins." A mere trace of these sub- 



