niPORTANT POISONOUS PLANTS 97 



Many of the plants in this list are certainly not strongly toxic but they 

 frequently produce injurious symptoms in man and animals. The list is by no 

 means complete; it will, however, serve the purpose of calling attention to 

 some of the injurious plants in North America. 



If may be noted in this connection that experiments recorded by no means 

 agree as to the effect of certain poisonous plants vipon animals. Notice the 

 very discordant results obtained with reference to the poisoning from loco 

 weeds. We may note also the opposite results obtained by experiments reported 

 by Dr. S. V. Nelson ^ with reference to feeding Delphinium Menziecii to sheep. 

 This writer concluded that when fed to sheep early in May it is not poisonous 

 to them. In the same report ^ Dr. E. V. Wilcox reports a very different ex- 

 perience. This writer reports an arrested heart action and respiration and 

 paralysis of the spinal cord. The animals were fed early in the season, about 

 the same time of the year that the unsuccessful experiments were reported by 

 Dr. Nelson. Either these writers were dealing with different plants or the 

 plant is more toxic in some localities than in others. Future experiments only 

 can determine. 



EUTHALLOPHYTA 



SCHIZOPHYTA 

 SCHIZOMYCETES. BACTERIA. 



Bacteria produce disease in two ways; — First, as parasites when they derive 

 their nourishment from' the living animal; in this case they may cause embol- 

 ism as in the case of Bacillus anthracis, or they may produce within the body 

 products, toxins that are poisonous, as the diptheria bacillus does. The tetanus 

 bacillus though parasitic produces powerful poisons tha.t when injected even 

 in minute doses cause a fatal termination, producing all the symptoms found in 

 animals having the disease. Second, many saprophytic bacteria produce poison- 

 ous substances, especially such as occur in putrid flesh, fish, and other decay- 

 ing substances. The listofsuch organism is a long one and cannot be given in 

 this connection. 



SCHIZOPHYCEAE. 



Osfillatoriaceae. Blue-green algae. 

 Oscillatoria. 



Several species in the U. S., probably somewhat injurious. 



Nosfocacae. 



Nostoc caeruleum Lyngb. 



N. muscorum, Ag. 



N. commune Vauch. 



Dr. J. C. Arthur some years ago thought that one of the common blue- 

 green algae, a species of nostoc, found in lakes in Northern Iowa and South- 

 ern Minnesota, was poisonous. Its poisonous nature was not conclusively 

 demonstrated. These algae have been suspected in other parts of the world. 

 Mr. George Francis calls attention to the Nodularia occurring in a fresh water 

 lake in Australia. Thirty ounces of a scum fed to sheep produced death. It 

 is also poisonous to horse, dogs and pigs. Many of the algae of this group 



1 Kept. Bur. An. Ind. 1898:421. 



2 I.e. 437. 



