CHKM;< LSIfl <F THK ANIMAL i;<>; 



3. Chromophanes. 



Tli-- '! above, tin- colou! M of th- 



lohule> which iM-eiir betwern the outer and inner limbs of th,. 

 r-tinal conea They are prepa: . .-t chiefly from tin- e\ 



l.inl>, a> follow. The retinas an- dehydrated with al... li.il and 

 extracted with ether. The ethereal -olution of the f : ,ts is then 

 evaporated tit dryness. tin- residue dissolved in hut alcohol : ,iid 

 saponified witli raustir soda. Tlu- haul ,.ij,> thus 



ol,tain.-.l a iv tlii-ii extract. -d in sii.-.-.->sion with j^tml.-uin 

 (see note p. 156), ether, and henxol. of these solv.-nt^ th- 



out the vellowish-;reen chloroj.hane. th i tlie 



yellow xanthoi.hane, and the third the ivd-eolouivd 



(i) ('lil<>f'i>li'iif Solul.lr in jM-tri.lelllii ether, ether, 

 hisulphide. and in alcohol. When dissolved in tin- tii 

 th'--e solvents it shows t\\o al.soijition hands K-tween /'and C , 

 in solution in tin- latter, tin- t\\o band> lie one each sidr of /' 



(ii) A'<'iit/t'>/i/iM. Soluble in ether, carbon bisulphide, and in 

 alcohol. In ethereal solution it shows only on,- absorption band. 

 near /', towards the blue end of the s]>ectruin. In carbon bi- 

 sulphide it shows similarly one band near, and to the blur, side 

 It is thus distinguished from the yellow pigment (lipochrin) 

 of the retinal epithelium previously deserihed. 



iii Ji'liii</j>liti,ii\ Soluble in turpentine, beniol, and in lodfaol, 



In ben/olic solution it shows one band close to, but on the red 

 side of./'; in solution in turpentine the band i- similarly 

 but now on the blue side of. /' 



Solutions of tbe chmniophanes ;nv slowly bleached by the ac- 

 tion of liu'ht. - chlorophane losing its colour fairly rapidly, xantho- 

 phane inoi-e slowly, and rhodojthane only alter prolonged exp> 

 In the. 1.-^ pure form in which the chroniopli t ob- 



tained by Kuhne, they ^ave the reactions which characterise the 

 lil'ochroines or lutein. \\/,. : (i) A tran-ient violet, foil- 

 bright blue, when treated with .//.-.///////.'/ sulj-huric acid . 

 tran-ient bluMi-^n-eii under the intluei; n^ (yell. .\\ i nitric 



arid, (iii) An initial uieen colour, passing into bluisli-^r--u. by the 

 action of a dilute iT. p. c. solution of iodine in dibit. 

 iodide of pota.-siuni.'-' In the jmrei form in which they \\ere sub- 

 sequently prejtared, Kiihiie found that they all t: th- 



tir>t of the abo\e ivartions, while Hone of then; I'.uied by 



the iotline solution, and in the cast- of rhodophane the second 

 reaction with nitric acid was scarcely marked 



......... \vrr-i. ' ' ' aii'l 



views a* to the i.l.-ntitv ..f thf-n- fattv ].i^ni.'iits \Mth Intcin. j.ir > thu 



H K , -.:.. / -. ,-. ,/. </. i>h>iii>l. Imttt. Hfxlrlf,. \M. iv. (1H2). S. 169. 



