POISONS AND POISONING. 65 



comparatively small dose is poisonous and ordinarily acts with great 

 rapidity. It causes respiratory paralysis and the animal dies in 

 convulsions. 



LAUREL. 



The laurels, including the broad-leafed laurel, Kalmia latifolia^ 

 the narrow-leafed laurel, Kalmm angustifolia^ the rhododendrons, 

 and other closely related plants are poisonous and cause considerable 

 losses. It is dangerous to let cattle graze where these plants are 

 abundant at times when other forage is scarce. The symptoms are 

 salivation, nausea and vomiting, spasms, dizziness, stupor, and death. 



FERN. 



The common brake or bracken fern, Pteris aqwilina^ has been con- 

 sidered responsible for the poisoning of many hoi^ses and cattle. 

 Many cases have been reported in England and Germany, and some 

 well-authenticated cases in the United States. Very little has been 

 learned experimentally of fern poisoning, but there seems to be little 

 question that it has been the cause of many deaths. The symptoms 

 are said to be temperature higher than normal, loss of appetite, 

 bloody discharges from mouth, nose, and bowels, and great depres- 

 sion followed by coma and death. Some authors say that the urine 

 is colored by blood. It is thought by some that the disease known as 

 " red water " in the northwestern United States and Canada is 

 caused by eating ferns. 



SORGHUM POISONING. 



Under certain conditions sorghum contains enough hydrocyanic 

 acid to make it exceedingly dangerous to cattle. These cases of poi- 

 soning most commonly occur when cattle are pastured upon the 

 young plant or upon a field where the crop has been cut and is mak- 

 ing a second gi'owth. .Conditions of drought make the sorghum 

 especially dangerous. There is some reason to think that the frosted 

 second growth is particularly rich in hydrocyanic acid. The cases 

 of poisoning occur when animals are grazed upon the plant, but not 

 from the harvested crop or from silage. If cattle are grazed on 

 sorghum or sorghum stubble they should at first be under constant 

 observation and should be removed as soon as any signs of illness 

 appear. Similar precautions should be used in grazing kafir. 



CORNSTALK DISEASE. 



Considerable losses of cattle have occurred when they were turned 



upon cornfields in the fall. Deaths come very suddenly and there 



is no opportunity to apply remedies. It has been thought that these 



fatalities, like those from sorghum, were caused by hydrocyanic acid, 



33071°— 16 5 



