32 BULLETIN 800, U. S. DEPAETMENT OF AGEICULTURE. 



death and 7 of illness. Four animals were fed repeatedly, No. 509 

 three times, No. 506 five times. No. 478 six times, and No. 522 

 fourteen times, besides receiving feedings of marc three times. 



It should be noted that Sheep No. 509 received the milkweed mixed 

 with hay and ate it, so that the feeding was distributed over a number 

 of hours — just how many was not determined. All the other sheep 

 were fed by the balling gun, so that the material was received in a 

 short time. There was, therefore, an opportunity for some elimina- 

 tion in the case of No. 609 and it may be expected that the effective 

 dosage would be somewhat greater than in the other cases; this 

 animal, after receiving smaller quantities in the preceding days, ate 

 0.22 pound per 100 pounds of animal between 11.10 a. m., June 22, 

 and some time before 8.30 a. m. June 23. 



Disregarding No. 509, however, and comparing only those sheep 

 which werQ fed by the balling gun, the smallest quantity that caused 

 symptoms was 0.148 pound with Sheep 506, and the largest quantity 

 given without effect, except in those cases in which stems alone were 

 fed, was to Sheep 522, 0.275 pound. 



The smallest dose that produced death was 0.138 p,ound in the ex- 

 periment with Sheep 483. It should be noticed that this lethal dose 

 was somewhat smaller than the smallest toxic dose. An average of 

 the fatal doses would not aid in determining the lethal dose, as an 

 evident overdose was given in some cases, but 6 of the cases were 

 killed by 0.184 p^und or less. 



From these cases it appears that the toxic dose is between 0.138 

 and 0.206 pound and that the lethal dose is from 0.138 to 0.22 pound. 

 All these figures are computed on the basis of the green plant for a 

 100-pound animal. 



It is evident that in Asclepias galioides we have an extremely toxic 

 plant with very little difference between the toxic and lethal doses ; 

 No. 468 was killed by the same dose from which No. 478 recovered, 

 and the smallest lethal dose is less than the smallest toxic dose in these 

 experiments. The fact, too, that so many of the experimental cases 

 died is evidence of the slight difference between the toxic and lethal 

 dosage. The same thing is indicated in the high mortality of the 

 range cases. The prognosis of poisoned cases is bad. In general, it 

 may be stated that a dose of anything above 0.14 pound for a 100- 

 pound sheep is liable to produce sickness or death. 



Glover, Newsom, and Robbins give tentative figures for the dosage 

 of 4 sheep, one of them dying on 63 grams, 0.139 pound, being prac- 

 tically the same as the minimum lethal dose of the authors lof this 

 paper. The weight lOf the sheep is not stated, however, and the plant 

 was fed with consequent wastage and inaccuracy. In the Salina ex- 

 periments all sheep were weighed and with one exception, Sheep 509, 

 the plant was fed by the balling gun, so that the data were quite exact. 



