48 N, H. AGR. EXPERIMENT STATION. IBulletin 183 



this calf began to show marked improvement and at the end of 

 the experiment, three weeks later, appeared to be in good con- 

 dition. It now exhibited no apparent effects of the ordeal, ex- 

 cept that it had been set back in weight and growth. 



Post mortem examination of the calf that died showed few 

 marked symptoms that could be ascribed definitely to poisoning 

 by the spray material. There was some emaciation and some 

 extravasation of blood into the walls of the small intestine. 

 Part of the small intestine showed a bluish green discoloration. 



SUMMARY AND DISCUSSION. 



It should be noted clearly that not all of the spray material 

 applied to the grass in the pens could have reached the stomachs 

 of the calves. It is true that in applying the spray care was 

 taken to direct it carefully on the grass within the plot. Never- 

 theless, a considerable part of the spray material must have 

 failed to lodge on the grass and have made its way to the ground 

 beneath. Second, there was interference from rain. Third, 

 altho in most cases the grass was eaten pretty closely in the 

 pens, it is impossible that the calves could have got all of it. 

 Furthermore, with the more concentrated doses the appetite of 

 the calves was so much impaired that part of the grass remained 

 uneaten. Fourth, the tramphng of the grass by the calves must 

 have dislodged part of the spray material after it had dried. 



How much this loss may have amounted to it is impossible to 

 say. It may easily have been 50 per cent. The points to be 

 noted are, first, that there must have been a distinct loss, and 

 second, that this would be the case in ordinar}^ field conditions 

 where calves or other live stock were pastured on grass beneath 

 sprayed trees. 



Examining now the amount of arsenic actually applied to the 

 grass in these several plots, we find the following: 



Where the material was used at the rate of 3 lbs. of paste to 

 50 gallons of water, the calves consumed the grass on 7 different 

 plots within a period of thirty-one days. To these 6 plots was 

 applied arsenate of lead, representing 65.8 grams of arsenic oxid, 

 AS2O5. This is the equivalent of 32.9 grams for each of the two 

 calves or 1.06 grams per calf per day. This amount represents 

 3.18 grams of dry arsenate of lead or 6.36 grams of arsenate of 



