Mr. J. McClelland on Indian Cyprinidae. 35 



which he made on the behaviour of vegetable colours to se- 

 veral liquids, more especially aether, oil of turpentine, and some 

 others, in the course of which several curious facts have been 

 brought to light ; the conclusions which M. Hiinefeld has 

 drawn, and which may interest us, are — the pigments of red- 

 dish yellow, or of rco/-yellow flowers, are probably all of an 

 extractive nature. 



For the examination of these colouring matters aether is a 

 very useful solvent. The variety of colouring of a flower or 

 leaf frequently arises from the deposition of one pigment over 

 the other, or from their mixture. [On this subject better in- 

 formation is to be had from the newer phytotomic works. — 

 Mey.~\ The principal change which the colours suffer in 

 withering, etc. appears to be, that the assimilation of carbon 

 only ceases by suppressed vegetation, while the absorption of 

 atmospheric oxygen becomes excessive ; for the easily oxidi- 

 zable extractive matters, and tannin in oxidized extractive 

 matter, become metamorphosed into gallic acid and into sub- 

 stances approaching more and more to humic acid, which 

 then destroy the pigments. 



M. Hiinefeld* has also made a series of experiments to learn 

 whether the formation of certain colours depends on iron con- 

 tained in the plant. Quantities (one or two ounces) of the 

 most different-coloured flowers were reduced to ashes. Some 

 of these flowers contained evidently iron and manganese, 

 others only iron, and traces of copper were found in the flow- 

 ers of Sambucus nigra, which had already been noticed. The 

 twigs and leaves of Sambucus nigra are said to contain no 

 copper, but a considerable quantity of iron. Traces of man- 

 ganese were found everywhere when sufficient quantities were 

 burnt. As these metals, says M. Hiinefeld, are found also in 

 white flowers, and their quantities stand in no relation to the 

 colours of the flowers, it seems that Meissner's theory is not 

 correct. There is probably no vegetable which does not con- 

 tain iron, and perhaps all the iron found in the human body 

 is derived from this source. 



[To be continued.] 



VII. —Indian Cyprinidae. By John McClelland, Assist- 

 ant Surgeon Bengal Medical Service f. 

 Dr. Patrick Russell published in 1803 an account of 200 

 species of fishes found chiefly on the coast of Coromandel ; 



* Beitrage zur Chemie der Pflanzenfarben. — Erdmann & Marchand's 

 Journal fur prakt. Chemie, 1839, 1 Bd. p. 84—87. 



f From the ' Asiatic Researches,' vol. xix. part ii. p. 217; having been 

 presented to the Asiatic Society of Bengal on the 5th of September 1838. 



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