POISONOUS PLANTS 267 



Chemical Diagnosis. — The vegetable toxines ricine, 

 crotine, and abrine, all possess the power of agglutinating 

 red blood corpuscles. In examining a cake or meal 

 suspected to contain castor seeds the powdered material 

 (about 2 grammes) is extracted by means of physiological 

 saline (0'9 per cent, solution of common salt) in the in- 

 cubator at 37° C. for a few hours, and the solution filtered. 

 The clear solution is then added to a suspension of red 

 corpuscles from fresh defibrinated, or citrated, blood suitably 

 diluted (about ten times) with salt solution. More or less 

 rapidly, according to the quantity of ricine present, the 

 corpuscles clump together, or agglutinate, and fall to the 

 bottom of the tube in the form of red flakes. With very 

 small quantities of material the phenomenon may be 

 observed in a hanging drop under the microscope. 



An alternative test consists in making a layer of a small 

 quantity of the suspected extract on the top of some serum 

 from an animal immunised to ricine. With ricine such a 

 serum forms a zone of amorphous precipitate (precipitin 

 reaction). 



PLANTS AND FOODS REPUTED TO BE POISONOUS. 



Some plants and vegetable foods are popularly spoken of 

 as poisonous, although no definite and specific toxic principle 

 can be associated with their action. In this section mention 

 will be made of the important substances which fall within 

 this category, and it may be remarked at the outset that 

 many of these so-called cases of poisoning prove, on 

 scrutiny, to be cases of injury or death due to errors in 

 diet, the bad preparation or condition of the ration, or the 

 greed of the subject. As to the last point, it ought always 

 to be remembered that animals, especially in periods of 

 scarcity of green food, or after winter feeding, eat freely 

 of any green plant they may encounter. 



Cotton-Seed Cake, op Meal. — Undecorticated cotton 

 cake is popularly described as poisonous. It has, in fact. 



