EXAMPLE 1 



Preparation of a Wholemount of a Mite by the 



Method of Berlese 



The use of the name Berlese in the heading of this example is less an 

 injunction to employ the mounting medium of that writer than it is a 

 tribute to the method of collecting small arthropods, which he introduced. 

 This method uses the "Berlese funnel." This device is a double-walled 

 funnel, between the walls of which warm water may be placed and 

 maintained at any desired temperature by applying a small flame to a 

 projecting side arm. The temperature is not critical, so that no thermo- 

 static mechanism is provided, but a thermometer may be inserted and 

 used to read the temperature at intervals. A circle of wire gauze with a 

 mesh of about % 6 in. is placed at the bottom of the inner glass funnel and 

 the material that is to be searched for mites is placed loosely on this 

 gauze. The lower end of the glass funnel is attached with modeling clav 

 to a tube containing whatever medium is being used for the collection 

 of the specimens. If the specimens are to be stored rather than mounted 

 at once, 96 per cent alcohol may be placed in the tube, and it is unneces- 

 sary to seal it at the base of the funnel. If, however, the specimens are to 

 be mounted at once in Berlese's medium, in which much better mounts can 

 be prepared from living than from preserved material, the tube must 

 contain water and be sealed to the funnel in order to prevent the more 

 active forms from working their way out of the tube. 



After the moss has been placed in position, a small lamp of not more 

 than 15 watts is mounted in any kind of a reflector some distance above 

 the material. The animals in the material, therefore, find themselves sur- 

 rounded by heat at the sides and plagued with light from above. As all 

 these animals are violently photophobic, they tend to move automatically 

 toward the lowest point of the moss, from which they drop down the 

 funnel into the tube. By this means it is possible in 10 or 15 min to collect 

 the whole fauna from a large handful of any organic material that would, 

 by any other means, take several hours to search. The use of the funnel 

 is not confined to moss but may be applied to hay, straw, shredded bark, 



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