8 BULLETIN 1332, U. S. DEPARTMENT OF AGRICULTURE 



Table 5. — Comparative toxicity of stock wormseed-oil emulsions of various ages i 



Age of stock emulsions in days 



Percentage of larvae killed by immersion in dip for 

 hours specified 





5 



6 



7 



8 



9 



10 



15 



1 . . 



50 

 75 

 100 

 100 

 75 

 75 



100 

 100 

 100 

 100 

 100 

 100 



100 

 100 

 100 

 100 

 100 

 100 



100 

 100 

 100 

 100 

 100 

 100 



100 

 100 

 100 

 100 

 100 

 100 



100 

 100 

 100 

 100 

 100 

 100 



100 



3 .. 



100 



14 



100 



23.. 



100 



30.. 



100 



40.. 



100 







1 All the emulsions subjected to this test contained 1 cubic centimeter of ascaridole to 6 liters of water. 

 The test was applied at a uniform temperature of 70° F. (21° C). A total of about 800 larvae were used 

 in the tests on which this table is based. 



COMPARATIVE TOXICITY OF THE INDIVIDUAL INGREDEENTS OF WORMSEED OIL 



As already stated, wormseed oil when distilled under a vacuum 

 of approximately 6 millimeters pressure can be separated by proper 

 technique and control of temperature into three fractions consisting 

 mainly of (1) terpenes, (2) ascaridole, and (3) a residue containing 

 principally ascaridole glycol. However, in separating the oil into 

 fractions for determining the toxicity of its several constituents, 

 four fractions were made, of which the first consisted mainly of 

 terpenes, the second of a mixture of terpenes and ascaridole, of 

 which the terpenes constitute the major portion, the third of prac- 

 tically pure ascaridole, and the fourth a residue consisting princi- 

 pally of ascaridole glycol. Data on the relative toxicity of these 

 ingredients are presented in Table 6. 8 



In making up the individual dips for the tests, material from each 

 fraction was emulsified with soap, using 10 cubic centimeters of 

 soap, 10 cubic centimeters of water, and 20 cubic centimeters of the 

 material, as was done with the wormseed oil in making the first 

 and most satisfactory emulsion in testing the stability of emulsions, 

 as recorded in Table 2. For each test to 6 liters of water was added 

 3.67 cubic centimeters of the emulsion. It will be noticed that all 

 the ingredients of the oil are toxic to the larvae. The ascaridole was 

 completely fatal to larvae in 5 hours, the terpenes in 8 hours, and 

 the residue in 12 hours. The results merely emphasize the fact 

 already stated that in buying oil of wormseed it is advisable to 

 purchase primarily on the basis of ascaridole content rather than on 

 that of price. 



8 With respect to the ascaridole glycol of the fourth fraction, the following excerpt from a letter from 

 G. A. Russell, by whom it was fractionated and assayed, may be of interest: " I have never done any work 

 on the keeping qualities of wormseed oil, but Nelson examined five samples of American oil which had 

 been shipped to Brazil and subsequently returned to the United States, all of which were at least 1 year 

 old. He found that the distillate residues, while higher than those found in fresh oil, were not excessive, 

 and concluded from this that the oil does not deteriorate very rapidly with age. It is my opinion that oil 

 preserved in well-filled containers will keep without appreciable change for a period of at least 1 year. 

 This glycol is formed by the rearrangement of the ascaridole molecules, and apparently is produced by the 

 action of the steam on the ascaridole at the time of distillation. This may account for the high percentages 

 of residue obtained when fractionating oils distilled by means of low-pressure steam over a relatively long 

 period of time." 



