26 TECHNICAL BULLETIN 149^ TJ. S. 0EPT. OF AGEICULTUKE 



mature, as indicated by the appearance of a deep yellow-green color 

 in most of the conidia. The disappearance of the toxin from cultures 

 and the rapid loss of potency after extraction indicate that it is of a 

 transient nature. This is shown in Table 2 and Figure 2. WHen 

 freshly prepared ether extract was fed to bees the entire lot died in 



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/ 2 3 * S' e 7 t' 



FionEH 1. — Rate of mortality of honeybees at daily Intervals after the commencement 

 of feeding with honey containing ether extract of the nutrient medium in which 

 Asjiergillus flavus had been cultured. The food was transferred to a new cage of 

 bees as soon as the bees of the previous trial were dead 



five days. Fifteen days later the same food was given to a second lot 

 of bees. This trial showed a death rate that was nearly normal for 

 caged bees. 



Table 1. — Length of life of iees in cages when ether extract of the culture 

 ■medium of Aspergillus fl(wus Aojc was mixed, with their food 



I Although this table mdlcates only that the bees of the first and second tests were dead after 24 hours, the 

 actual time was 10 hours in the case of the first trial and 18 hours in the second. 



Table 2. — Length of life of 'bees in cages when ether extract of the m^edmm in 

 which Aspergillus Jlavus Ao5c had been cultured was mixed with their food 



GMoroform extract 



To find whether poisonous organic bases or other poisonous sub- 

 stances soluble in chloroform were present, the liquid nutrient me- 

 dium (Leonian's formula) was thoroughly drained from half a 

 dozen flask cultures of the mature organism, Aspe'rgiUus flavus Ao5c. 



