POISONOUS PLANTS 253 



acetic acid solution. A dark colour zone forms at the 

 junction of the liquids, and in about two minutes a blue 

 colour ring, whilst after about thirty minutes the whole of 

 the upper (acetic) layer has a deep indigo blue colour, 

 gradually passing to blue-green. Various tannins, especi- 

 ally from the quinine barks, give a similar reaction, as 

 also does formaldehyde. A physiological test on a frog is 

 therefore needful in a case of doubt, or for strict medico- 

 legal purposes. 



EEFEBENCES TO DIGITALIS. 



> W. Graham Gillam, Vet. Beoord, 1906, p. 88. 



2 Damman andBehrens, Vet. Jl., 1903, p. 78.* 



3 W. Pauer, Vet. Becord, 1896, p. 698. 

 * H. Olver, Veterinarian, 1872, p. 173. 



Verbaseum, Scrophularia, Gratiola, and LinaFia. 



These genera do not contain plants which give rise to 

 serious poisoning, and, moreover, have not received precise 

 study, A brief mention will therefore suffice. 



Verbaseum. — Verbaseum Thapsus, or great mullein, is a 

 common roadside weed, extending as far north as Aberdeen. 

 The leaves and flowers afford an emollient and expectorant 

 extract, which is used as a medicine. The seeds are stated 

 to be narcotic, but animals refuse to eat the plant 

 (Cornevin). 



SCPOphularia. — Scrophularia nodosa, or figwort, and 

 S. aquatica, or water scrophularia. The former occurs in 

 woods, the latter in marsh or moist situations, and has a 

 disagreeable odour. According to Walz, they contain bitter 

 principles, scrophularin and scrophulerin respectively, which 

 may cause fatal superpurgation. But the plants are not 

 eaten by animals. 



Gratiola. — Gratiola offieinalis, or hedge hyssop, is found 

 in Europe, and in the Southern United States. It owes its 



* This is a remarkable case, in which three out of eight sheep 

 died after eating garden chppings, including Datura Stramonium, 

 Hyoscyamus albus, and Digitalis purpurea. 



