504 Georgina Siveet : 



good. Very often, however, the reagent which makes clear one 

 structural detail is useless for some others, so that I always 

 examine each species in several reagents. That most commonly 

 used for Nematodes and most generally satisfactory, especially 

 where time is a consideration, is what I have called carbolised 

 absolute — i.e., a mixture of 80 per cent, of pure carbolic acid 

 and 20 per cent, of absolute alcohol, used also. I believe, by 

 Dr. N. A. Cobb. It is unfortunate that this substance cannot 

 be used for clearing preparatory to mounting in balsam. For 

 purposes of measurement this carbolised absolute is more satis- 

 factory than any other of Avhich I know, except, perhaps, 

 caustic soda and 20 per cent, glycerine, the two former sub- 

 stances retaining the full size and shape of the v.'orm better 

 than any of those mentioned above. In order to determine 

 the reagent best retaining the proportions and full size of the 

 animal, I made a series of experiments with Nematodes, with the 

 following results. Taking the length in carbolised absolute as 

 100 divisions of a scale, and the width as 4.9 divisions, I found 

 the variations to be as follow : — 



Carbolised absolute - 100 divisions x 4. 9 divisions. 



Caustic soda (50%) - 100 4.8 



Glycerine (20%) - - 99 4.9 



Absolute alcohol - - 96-97 4.8 



Glycerine (pure) - - 95 3.7 



Oil of cloves - - - 94 4.9 



Xylol - - - - 93 4 



Cedar oil - - - 87 3 



v' 



(These reagents were not used consecutively on the same 

 worm.) 



Since evidently there is less shrinkage and distortion from the 

 use of carbolised absolute than of the other reagents mentioned, 

 I have made all my measurements in this fluid. 



The methdd of descri])tion and record can be seen at a glance. 

 In giving tlie synonyn)y, it is my jmrpose to give it in full 

 wherever possible, with the original dates also, though in the 

 early stages of this work it is not always practit'able, as there 

 is so much of the literature as vet unoljtainable in Australia. 



