LARKSPUR POISONING OF LIVE STOCK. 75 
Although Delphinium barbeyi was common in the pasture, no trouble 
had been experienced from this source, probably because there was 
an abundance of good feed. Moreover, none of the experimentally 
fed animals had been poisoned since August 8, on account of the 
diminished toxicity of the plants. The autopsy showed that No. 633 
had died of asphyxia, as it had vomited, and the stomach contents 
were found in the larynx and trachea. As the animal had been dead 
for two or three days, the autopsy was unsatisfactory, but, so far 
as it could .be made, showed conditions typical of larkspur poisoning. 
A careful examination of the contents of the rumen demonstrated 
the presence of a large amount of stems and seeds of Delphinium 
harbeyi. This, then, was clearly a case of larkspur poisoning in 
which the seeds were the most important factor, for it was too late 
in the season for the leaves to produce poisoning. 
AGE OF PLANTS AS AFFECTING TOXICITY. 
From a careful examination of the charts for the feeding of 
Delphinium harbeyi and Delphinium menziesii certain facts are 
brought out quite clearly in regard to seasonal changes in toxicity. 
If an average curve were made for the charts of Delphinium barbeyi 
feeding in 1909, 1910, and 1911 (figs. 6, 7, 8, 10, and 11), it would be 
found that the quantity necessary to produce poisoning increases pro- 
gressively from the first of the season until the time when seeds are 
formed in the plants. Taking into account the length of time 
during which the plant was given in individual cases, the appar- 
ently aberrant cases of very large quantities in these years are easily 
explained, as, in those cases, by reason of the prolonged feeding, 
there was more or less elimination of the poison. 
It is a striking fact that the smallest quantity needed to produce 
poisoning was in the earliest cases. It seems quite clear that Del- 
phinium barbeyi progressively loses toxicity after blossoming until 
the time when the seeds are formed. At this time the leaves and 
stems are not particularly toxic and if the seeds were disregarded, 
the curve would indicate diminished toxicity from early in the 
season until the middle or last of August, at which time on the Colo- 
rado ranges the plant becomes perfectly harmless. 
As a matter of fact, stock on the range do not eat the seeds of 
Delphinium barbeyi to any extent, so that the fact that the seeds are 
especially toxic has little practical bearing so far as the stockmen are 
concerned. It may be stated as a general fact that after the middle 
or latter part of August, depending upon the season, Delphinium 
barbeyi ceases to be poisonous, and under ordinary range conditions 
in Colorado few cases of poisoning occur after the middle of July. 
Not only does it cease to be injurious, but it has been noticed that 
