Tech. A:3 



This is necessary in orJor that tlie oil immersion objective, 

 which has a veiy limited working distance, may be focused on and 

 within the nematode without contacting the cover-glass. An 

 excellent means of supporting the cover-glass is by use of short 

 lengths of glass-wool fibers. Glass-wool is readily obtained 

 and will be found to have strands of various diameters, so that 

 supports of the optimum thickness can be selected. Thick sup- . 

 ports can be made from pieces of cover-glasses which come in 

 various thicknesses, pieces of slides, pieces of drawn glass rod 

 or tubing, plastic, or from numerous other materials. 



One method of support is to apply a ring of ZUT or other inert 

 material to a slide, making a shallow well of desired depth. 

 This involves some practice in getting support of the correct 

 thickness. This method is worthy of consideration and refine- 

 ment to a more controlled degree, as it offers certain advantages, 

 particularly to the beginner, in the preparation of good slides. 



C. Additional Special Laboratory Equipment: 



1. Manipulation of nematodes , individually and without harm, can be 

 done in either~of two ways. They can be picked up on needles of 

 one kind or another or drawn up into a fine-tipped pipette, pro- 

 vided with a rubbir bulb or connected to a tube and mouthpeice 

 for oral operation. The use of a needle is usually preferred, 

 because liquid is unavoidably carried over with the nematodes, 

 when a pipette is used, which may not be desired. 



Ordinary sewing needles of fine size can be used when inserted 

 in a suitable holder. They are improved by oxidizing in an open 

 flame which roughens the needle siurface. Cacti needles are 

 excellent, although not always readily obtained. Bristles, . 

 strands, or loops of hair mounted in a holder have also been used. 



Long a favorite with nematologists has been the use of a needle 

 whittled from barnboo. Using a razor blade and observing progress 

 under the dissecting microscope, it is oossible to get a very 

 fine-tipped needle which is probably unsurpassed for picking such 

 tiny objects as nematode eggs out of water. Leaving the outer 

 hard covering of the bamboo piece as the actual needle end gives 

 added resilience and moisture resistance to the needle. 



A very durable and satisfactory needle for manipulating larval 

 and adult nematodes has been found in the use of dental pulp 

 canal files. These spring metal, needle-like files can be fur- 

 ther improved by grinding or filing the tips to a fine point and 

 by slightly bending the^last eighth of an inch or so of the tip. 

 A local dentist may have such pulp canal files in stock or may 

 be able to procure them from his supplier. The manufacturer of 

 these files is the Kerr Manufacturing Cto., Detroit 3, i'lich. The 

 ■•;. A. Lockvjood Dental Co., 1722 "I" Gt., I'J.W., V/ashington, U. C, 



