SECTION TWO 



LIGNIN PINK 



For whole mounts of marine invertebrates, particularly for 



crustaceans limbs, ostracod appendages. Medusa of Obelia, 



etc., as well as for demonstrating chitin 



Solutions required: 



A. Sea water Bouin : 



Sea water saturated with picric acid 75 ml. 

 Formaldehyde 40% . . . . • • 25 ml. 



Glacial acetic acid . . . . • • 5 rnl' 



B. Lignin pink saturated in distilled water or 

 in Benzyl alcohol. 



Technique: 



1. Specimens are fixed from eighteen to forty-eight hours, 

 according to the material, in Solution A. 



2. Wash out the fixative with 50% alcohol, followed by 70% 

 alcohol until the yellow coloration, due to the picric acid, is com- 

 pletely extracted. 



3. Wash in running water to remove the alcohol. 



4. Immerse in solution B for fifteen minutes or longer. 



Results: 



With the aqueous solution of the stain 



Medusa of ObeHa and limbs of crustaceans are stained deep 

 carmine colour. The finest structures of ostracod appendages, 

 uniform pink, but a better effect can, however, be obtained by 

 staining the specimen for a longer period (up to sixteen hours) 

 with a solution of the dye in benzyl alcohol : the final result in this 

 case is a definite purple for the exoskeleton, while the other tissues 

 are carmine colour. 



Note: Overstaining with lignin pink is impossible, and it will not 

 wash out with alcohol. 



Reference: Cannon, H. G. (1941). 



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