no SCIENCE PROGRESS 



Harris have lately succeeded in isolating a very pure ricin, 

 associated inseparably with the coagulable albumin. Its 

 toxicity was so great that TTJ Vtr m g- ( = 0*000001 gramme) per 

 kilo, of rabbit proved fatal. The fact that its toxic action 

 disappears after digestion with trypsin and after heat coagula- 

 tion is strongly suggestive of its protein nature. 



2. Abrin. — This toxin is contained in the seeds of Abrus 

 precatorius, a tree growing in tropical countries. The seeds are 

 known as Jequirity beans. In 1889 Sidney Martin isolated 

 their toxic principle, and considered it as a mixture of a globulin 

 and an albumose. It is also highly poisonous. 



3. Crotin has been prepared in a similar way to ricin and 

 abrin from the seeds of Croton tiglium (Malabar beans). 



4. Robin is contained in the bark of Robinia pseudo-acacia. 

 It has been isolated by Power, who considered it to be nucleo- 

 protein. It shows all the protein reactions, and its aqueous 

 solution coagulates on boiling, thereby losing its toxicity. 



A true phyto-toxin of a protein nature called Phallin seems 

 to be contained in the mushroom Amanita pkalloides, different 

 in its action and chemical behaviour from the alkaloid mus- 

 carine found in Amanita muscaria. The toxin causing hay- 

 fever must also be mentioned in this connection. According to 

 Dunbar this also is a protein (albumin) contained in the pollens 

 of various grasses and cereals. 



These phyto-toxins have been of the greatest use in the 

 study of immunity, since their action is similar to that of 

 animal and bacterial toxins. Like the latter they give rise to 

 haemolysis and agglutination, and as these phenomena can be 

 studied outside the body in test tubes, they have been especially 

 valuable for systematic investigations. Ehrlich showed in 1891 

 that it is possible to immunise animals against these toxins, 

 and this observation furnished the starting-point for his funda- 

 mental investigations regarding immunity. Immunisation is 

 obtained not only by subcutaneous injection, but. also by feeding 

 or by direct application to the eye. The anti-bodies formed 

 in the blood plasma of the immunised animal are also of 

 protein nature, and may be fractionated by \ — \ saturation with 

 ammonium sulphate. It is interesting to note that the animal 

 organism is only able to produce these "anti-toxins" against 

 poisons of a protein-like character. All attempts to produce in 

 the organism an anti-toxin against poisons of known chemical 



