274 Mr. Gray on the Slender-tongued Saurians. 



the greater or less quantity of stem that had been buried and 

 is now gathered and sold with the root." 



The authors who have most fully treated this subject, how- 

 ever, regard the roots as imbued with a red colour while grow- 

 ing, and undergoing no change in this respect from subsequent 

 circumstances. Many manufacturers, ignorant of this fact, 

 to whom I submitted my observations, and showed the roots 

 passing through all the stages of colour up to that which they 

 attain when reduced to powder, while they formerly exhibited 

 no trace of a red hue, have positively assured me that this re- 

 mark would certainly lead to modifications in their manufac- 

 ture. The assumption of a red colour is therefore a chemical 

 phenomenon quite independent of vitality, while the yellow 

 hue, on the contrary, seems to arise from a vital action which 

 forbids the first ; thus, if I place, for comparison, two portions 

 of root, one living and the other dried, in a bottle, the former 

 will preserve its yellow hue, while the second turns red, and 

 in two days ends by acquiring a violet tinge. 



Finally, the better to establish the vital power of the cells, 

 and to prove that the production of the colouring principle 

 was entirely determined by their peculiar action, I caused two 

 young madder plants to germinate in distilled water ; they 

 grew very little, but the tissue of their roots notwithstanding 

 secreted a yellow fluid, the tint of which seemed to me quite 

 as decided as in young plants of equal size raised in earth. 

 This colouring therefore depends on a peculiar action of the 

 cellular membranes, to solve which it would be necessary first 

 to solve that hitherto inscrutable problem of the vital powers*. 



XXX. — Catalogue of the Slender-tongued Saurians, with De- 

 scriptions of many new Genera and Species. By John 

 Edward Gray, Esq., F.R.S., Senior Assistant in the 

 Zoological Department of the British Museum, &c. 



The Saurian reptiles may be divided into two nearly equal groups ; 

 one having a short, thick, slightly-nicked papillary tongue, and the 

 other a more or less elongated forked tongue. 



* [We shall reserve the author's analysis of the stems for a future Num- 

 ber of the Annals. — Edit.] 



