Tec?). I<;:2 



Fixation of the nematodes after relaxing is accomplished either by- 

 transferring the nematodes to the fixative or by removing the excess 

 water from about the nematodes and adding the fixative. Nematodes 

 concentrated in the bottom of a centrifuge tube or settled in a vial 

 of water are fixed by the addition of a volime of double strength 

 fixative equal to the volume of water present in the tube or vial. 

 Mijx the contents promptly by shaking. 



Formxilae for various commonly used fixatives and mounting media are 

 given with notations on their use. 



Formalin Fixative 



5/0 formaldehyde is the concentration most frequently used and is pre- 

 pared from: 



Stock formalin 5 ml. 133 ml. 



(37.5^ formaldehyde) or 



i"/ater 32.5 ml. to make one liter 



The nematodes can be transferred directly to a drop of this fixative on 

 a slide, glass-wool supports added, and the coverglass sealed carefully. 

 This type of slide mount may last for as long as several months or 

 longer. Distortion of the cuticle and of the oesophagus may be noted 

 for some species when fixed and preserved in this material. This has 

 for many years been the fixative used for routine identification work, 



TAP Fixative 



(Courtney, Polley, and Miller 1955): 



Water distilled 91 ml. 



UO^ commercial formaldehyde solution 7 ml. 

 Triethanolamine 2 ml. 



This new fixative, called TAF (triethanolamine formalin), has given 

 excellent fixation and preservation of specimens which have lasted for 

 more than two years. It is said to eliminate the objectionable features 

 of the ordinary S% formaldehyde solution. 



Living nematodes may be placed directly in the cold fixative, or they 

 may be first relaxed. Although it is still too soon to know how long 

 permanent slides of nematodes fixed in TAF will last, good slides have 

 been obtained by the modified process of Baker, which is included in 

 this section of the manual. 



Formalin - Aceto - Alcohol 



Numerous variations of this popular type of fixative have been used 

 for fixation of nematodes, one recomra ended proportion is: 



