1917-] C. R. N. Rao : Iridocytes in Batrachian Larvae. 289 



VIII. Hydrochloric acid solution of guanin on heating turns 

 red and the guanin hydrochloride — the ash obtained after boiling 

 — is slightly reddish, which treated as in experiments V, VI and 

 VII gives similar reactions. 



IX. Potassium permanganate solution treated with nitrate 

 of guanin, with a touch of caustic soda. The green solution (green 

 being due to the formation of K.^Mno^.) on heating gives an albu- 

 minous flocculent red precipitate (oxyguanin) which is insoluble 

 in water, rectified spirit and weak acids (Watt). 



X. The same reactions are obtained with the hydrochloric 

 acid solution of guanin. 



If any of these precipitates obtained with silver nitrate in the 

 above experiments should be treated with oxyguanin obtained in 

 experiment X, the silver chloride is precipitated in the form of a 

 white stuff. 



The iridocytes are insoluble in water, ether, chloroform, gly- 

 cerine ^ and acetic acid, but soluble both in acids (Nitric, Hydro- 

 chloric and Sulphuric) and bases like caustic potash, soda and 

 ammonia. Formalin and alcohol are also solvents. 



With the alkaline (NaOH) solution of iridocytes and argen- 

 teura the following additional reactions and properties were ob- 

 tained. 



XI. The solution was treated with strong picric acid and 

 boiled for a few minutes. The whole turned into orange red on 

 being allowed to stand for 18 hours. 



XI r. With potassium permanganate solution the usual green 

 reaction results. On boiling, the red flocculent precipitate is ob- 

 tained even without the addition of any acid. 



XIII. To the alkaline solution of iridocytes, potassium ferri- 

 cyanide (K3fe(CN)J was added and boiled for about 15 minutes. 

 Silver nitrate being added gives a white precipitate. Reboiled the 

 precipitate is transformed into bright red, 



XIV. NaOH solution of iridocytes (C5H5N5O) on boiling slow- 

 ly turns reddish and the addition of another base like NH., and 

 reboiling turns the red into purple, 



XV. A white ash is deposited on the sides of the test tube 

 when the above solution (KOH or NaOH C5H5N5O) is boiled to 

 dryness. The calcified substance is refractory to concentrated 

 acids and aqua regia; it dissolves, however, on heating, setting up 

 a vigorous chemical action. 



The next point which is worthy of notice is the fact that 

 calcium in any form is absent from the argenteum of the larvae of 

 M. ornata and M . rubra which has therefore nothing to do with the 

 guaninkalk of Ewald and Kriikenberg, Solutions of the subcuta- 

 neous tissue from the abdominal surface of the Ranid larvae react 

 to the calcium tests and the dead white of the skin is due to 

 guaninkalk in these cases. Guanin is silvery white, and the golden 



i Iridocytes mounted in glycerine broke up and crystals were found at the 

 end of a fortnight. 



