72 BULLETIN 365, U. S. DEPAETMEoSTT OF AGEICULTUEE. 



not safe, however, to draw any definite inference in regard to this. 

 The toxic dose in the experiments with Delphinium cucullatum 

 varied from 22.7 pounds to 49 pounds. This apparently indicates a 

 greater toxicity for this species than for the Colorado larkspurs. 

 The experiments were few in number, however, and all taken during 

 the time of probable maximum toxicity of the plant, and it seems 

 likely that a wider experience would show greater conformity to 

 the standard of the Colorado plants. 



It is somewhat surprising to notice how great a quantity of lark- 

 spur must be eaten in most cases before poisonous effects are pro- 

 duced, and this fact may perhaps be the explanation of the cases 

 which are frequently recorded of the passing of succeeding herds 

 of animals over the same poisonous area, some being poisoned and 

 others going without any harm whatever. It seems very probable 

 that the animals showing the symptoms of poisoning may have come 

 to these areas when particularly hungry and that individuals on 

 this account may have eaten large quantities of the poisonous weed. 

 It is well known that a ruminant when very hungry will eat enor- 

 mous amounts of material which attracts it. It is also well known 

 that under these conditions animals are more apt to take the plants 

 which are most prominent, and if the larkspm^s were more con- 

 spicuous than other forage plants it is very probable that the animal 

 under such conditions would eat an unusual quantity and conse- 

 quently suffer. The practical inference from this is that in handling 

 cattle care should be taken not to drive them over a supposed poison- 

 ous area when they are particularly hungry. On this account it 

 would doubtless be better to make the drive over such an area in 

 the afternoon rather than in the morning. It will be noted, too, that 

 the quantitj^ which may be poisonous varies within very wide limits, 

 and that an animal may suffer from eating not more than 25 or 30 

 pounds. Perhaps special emphasis should be placed upon the fact 

 that the toxic dose is quite large. The larkspurs are not violently 

 poisonous plants and may be eaten in quite large quantities with no 

 bad results. Because a region contains some larkspurs it is not 

 necessarily a dangerous locality for grazing. The region is dan- 

 gerous only when the plants are present in considerable numbers 

 or when there is. a lack of other forage so that the cattle eat the lark- 

 spur in large quantities. Delphinium menziesii in some localities is 

 so scattered that it can do no harm. This is true of areas in southern 

 Utah. AVliile Delphinium, hicolor, the low larkspur which is charac- 

 teristic of the region about the experiment station at Grey cliff, un- 

 doubtedly has the same poisonous properties as the other larkspurs, 

 it does not grow in that region in sufficient abundance to cause any 

 harm. It occurs in scattered groups of a few plants and it would 

 be impossible for cattle to get enough in grazing to produce intoxica- 



