236 VETERINAEY TOXICOLOGY 



nicotine. The family thus includes many of our commonest 

 and most dangerous poisonous plants. Each is represented 

 in America, and Oestrum nocturnum in South Africa, whilst 

 datura is a common Indian poison. 



Active Principles. — Before proceeding to details regard- 

 ing each species it will be convenient to describe the active 

 principles of the plants involved, which from this point of 

 view may be divided into three groups — (1) the atropine 

 group ; (2) the solanine group ; (3) the nicotine group. 



(1) The atropine group comprises the genera Atropa, 

 Hyoscyamus, and Datura, and the species Atropa Belladonna, 

 Hyoscyamus niger, and Datura Stramonium. They contain 

 alkaloids, or mixtures of alkaloids, of the atropine group. 

 These are atropine, hyoscyamine, hyoscine (also called 

 scopolamine), and atroscine (also called i. -scopolamine). 

 They are very closely related chemically and also physiolo- 

 gically, and form the mydriatic, or pupil-enlarging, group. 



(2) The solanine group comprises the genus Solanum, and 

 the species S. dulcamara and S. nigrum, found wild, and 

 8. tuberosum (potato), S. lycopersicum (tomato), and S. melon- 

 gena (egg-plant) cultivated. They all contain the gluco- 

 sidal alkaloid solanin, allied to the saponins, but containing 

 nitrogen, and resolvable into a sugar and an alkaloid sola- 

 nidine. Like the saponins, solanin is colloidal, and not 

 easily absorbed through the intact alimentary mucosa. 

 But solanidine is easily absorbed. 



(3) The nicotine group, represented by tobacco, contains 

 the volatile alkaloid nicotine, allied chemically and physio- 

 logically to Conine. 



Atropa. 



Botanical ChaFacters. — Atropa Belladonna (Fig. 82), 

 deadly nightshade or black cherry, reaches about 3 feet, 

 has an herbaceous stem, ovate leaves, solitary dark purple 

 flowers, and black berries. It frequents waste, stony places 

 in chalky districts, the vicinity of old castles and ruins, and 

 is rather local in the South of England, rare in the North, 

 but common in the South of Europe. 



