32 BULLETIN 125, U. S. DEPAETMENT OF AGRICULTURE. 



In the compilation of Tables II and III some of the cases have been 

 excluded. In Table II all cases in which the remedy given was 

 clearly effective were excluded, for some of these received what would 

 have been a lethal dose had it not been for the remedy. In Table III 

 cases were excluded which were known to have received much more 

 than a lethal dose. The uniformity of dosage in 1914 is explained by 

 the fact that the preceding work had shown clearly that the toxic 

 dose was not far from 0.5 pound, and the experiments were made on 

 this basis. It should be noted, too, that most of the work of the 

 summer of 1914 was with reference to the experimental use of reme- 

 dies, so that the quantity of the plant administered was estimated 

 to be sufficient not simply to produce symptoms, but to make the 

 animal very sick, in order to get a fair test of the remedy. Hence, 

 the average figures for the toxic dose will be rather high. 



The " forced feeding" cases of 1914 can be fairly compared with the 

 "drenched" cases of 1912 and 1913, as the difference between the 

 two methods is mainly in the fact that in forced feeding no water is 

 used while in drenching considerable water is necessary as a vehicle 

 for the weed. 



The age of the animal played a comparatively small part in these 

 experiments, as all the animals were mature, most of them being 2 

 years old or older. 



It will be noticed that when the plant was given in the form of a 

 drench or by forced feeding, the dosage, as would be expected, was 

 considerably less than when it was given with food. An examination 

 of the complete table of feeding (Table I) shows also very clearly that 

 the size of the dose varied inversely with the time during which the 

 material was eaten. In a large number of cases in which the plant 

 was given with food, the feeding extended over two or more days. 

 In those cases the dosage was considerably greater than when the 

 material was fed in a single day. It may be assumed that if the 

 same quantity of the plant which was received in a drench could 

 have been fed within a short period of time, the effect would have 

 been the same. 



The average dose which produced illness when administered in the 

 form of a drench or by forced feeding was practically the same for 

 all parts of the plant except the pods and seed. It appears that the 

 plants are less toxic at the time when the pods are forming, which may 

 be due, in part at least, to the diminished toxicity of the leaves as they 

 dry up. It is not clear, however, from this work, that the leaves lose 

 any appreciable amount o£ toxicity, and the more probable explana- 

 tion is that the pods at this time are only slightly toxic. In the single 

 experiment of feeding pods without seeds, the dosage was about like 

 that of other parts of the plants, but it is probable from the detailed 

 history of this experiment that this is not a fair representative of such 

 cases. 



