EXPERIMENTS WiTfl DIFFERENT EXTRACTS AND DECOCTIONS. ] 83 



the purpose intended, yet we are not without hope that some of them 

 will ultimately prove valuable additions to the list of insecticides from 

 tlie vegetable kingdom. 



^o uniformity in preparing the extracts and decoctions was required 

 from the agents of the Commission, as we deemed it best to have them 

 prepared in different ways and in various proportions. This may ex- 

 plain, in some measure, the discrepancy in the results obtained. 



Mr. James Eoane prepared during his stay at Selma a large number 

 of extracts, decoctions, and infusions, reporting as follows in regard to 

 their preparation : '^ My infusions and decoctions are made in various 

 degrees of concentration, while the alcoholic extracts (prepared by 

 macerating the crude drugs in one part of pure alcohol and one part 

 water for fifty hours and then subjecting them to a strong pressure in 

 a screw press) have been made of uniform strength — of the green leaves 

 four ounces being taken to the pint ; of the dried, two ounces. In all of 

 my preparations I have used the leaves and herbal parts of the plant, ex- 

 cepting the bark of the root of sassafras and the berries of the China 

 tree. The decoctions and infusions have been made in quantities rang- 

 ing from two quarts to a gallon and the alcoholic extract invariably a 

 pint." 



These preparations, amounting in all to forty-eight, were tested at 

 Selma, Ala., during the months of July, August, and September, by Mr. 

 Schwarz. 



Professor Jones prepared at Oxford a smaller number of vegetable 

 extracts and decoctions, mostly from the same species of plants used 

 by Mr. Eoane, the preparations being made in various degrees of 

 strength, the plants or parts of the plant being first carefully dried in 

 the shade. He tested them himself at Oxford on the Cotton Worm as 

 well as on other injurious insects, and sent also a supply for experi- 

 mentation to Selma, Ala. Professor Jones's decoctions were made in 

 large quantities, so that they could be used on an extensive scale. 



Similar experiments were conducted by Dr. Barnard, at Ithaca, K. T., 

 with a small series of extracts prepared by him. As he had no Cotton 

 Worms at hand he tested his preparations on various other insects, 

 but he forwarded samples to Selma, Ala., where they were also tested 

 on the Cotton Worm. 



Finally, Professor Stelle briefly gives in his report the results of a few 

 experiments with vegetable preparations made during his stay in Texas, 

 while a few other experiments made by Mr. Schwarz, in 1879, have al- 

 ready been recorded in the first edition of this work. 



The effects of these substances on the Cotton Worm may be threefold 

 first, they may kill it by contact ; secondly, they may, like the mineral 

 poisons, act through the stomach; thirdly, they may render the leaves 

 of the plant so distasteful to the worms as to drive these from the 

 plant. Effect upon contact is easily observable even where not fatal. 

 It usually takes place very soon after application, and it may safely be 



