Tech. C:)4 



and a complete d'^scription of the elutri?tor apparatus is available 

 (SeJn.horst, 1956). 



The elutriator apparatus was developed for work involvinp removal 

 of a high percentage of nematodes from heavy clay soils; two of the 

 most troublesome aspects of soil processing. The elutriator appa- 

 ratus works well with all kinds of soil, resulting in a high rate 

 of removal, of the nematodes. The resulting samples will be found 

 to be much freer from debris and silty water. Another noteworthy 

 feature is that this can be a standardized technique, yj.elding 

 more comparable results between any laboratories equipped with the 

 elutriator apparatus. 



The accompanying illustrations will assist in planning an installa- 

 tion of this apparatus in having the glassware and multiple sieves 

 fabricated. One source for obtaining the glass items and suitable 

 rubber stoppers is llr. D. E. Sampson, Scientific Supply Room, Uni- 

 versity of North Carolina, Chapel Hill, North Carolina. If no 

 special device is used for holding the rubber stopper at bottom of 

 the glass column, difficulty in keeping an ordinary rubber stopper 

 in place against the weight of the water and soil may result. A 

 special kind of stopper, stocked by Arthur H. Thomas Company, will 

 hold in place vrell. (Semi-solid type, Catalog No. 8806, HR-IO8, 

 size lOj.) The elutriator glassware parts diagrammed have to be 

 made by a glassworker but represent a design suitable for standard 

 glass materials available in this country. 



The diagram of an installation consisting of a bank of five elu- 

 triators illustrates a convenient arrangement, utilizing readily 

 available materials and incorporating design features suggested by 

 Dr. Seinhorst. The photographs are used with the permission of 

 Dr. Seinhorst and illustrate two types of multiple sieves which vrill 

 be of use to anyone who uses sieving whether as a part of the Sein- 

 horst elutriator method or in the other methods described. Having 

 the sieves stacked in this manner obviously results in a great 

 saving of time and labor while retaining the desired feature of 

 several passages of the nematode suspension through the fine-mesh 

 final sieve. One person using the bank of five elutriators as 

 illustrated can routinely process at least forty-five samples per 

 work day. 



It is advisable to purchase a duplicate set of the flasks and the 

 stems which fit the flasks so that a second lot of samples can be 

 prepared while one set is being processed in the elutriator. Also, 

 these portions of the apparatus are the most subject to breakage. 



Another aspect of this method that should be noted by all who apply 

 the Baermann funnel method for a final cleaning and concentrating 

 step is the utilization of petri dishes in place of the funnels. A 

 simplification of the procedure discribed by Seinhorst that has been 

 tested and found very satisfactory is to pour the accumulated wash- 

 ings of the final sieves directly on to a double thickness of Scott 



