Apr. 1896.] BOTANIC.\L SOCIETY OF EDINBURGH. 539 



pigments, in the case of flowers and fruits, are called 

 respectively anthoxanthin and xanthin, though their distinct 

 nature must be regarded as doubtful. They are always 

 associated with chromoplasts, which, as is now well-known, 

 frequently originate from modified chlorophyll corpuscles. 



Looking generally at the lipochromes of phanerogams, 

 we may say that, while little is known of individual 

 pigments as a whole, they resolve themselves into two 

 series. The one includes orange to orange-red pigments, 

 which are little soluble in cold alcohol, but are readily 

 soluble in chloroform and benzol. Of these, carotin is the 

 type. The other series includes yellow^ pigments, which, 

 according to Courchet (2) are not readily crystallisable, 

 and which are readily soluble in cold alcohol, but less 

 soluble in benzol and chloroform. Of these, xanthophyll, 

 if it be a distinct pigment and not a mixture, is the type. 

 As to the relations of the two series it is not yet possible 

 to say much, but it is not improbable that further investi- 

 gation will show that the members of one series can be 

 readily transformed into members of the other, and that 

 this occurs both in the living tissues, and as a result of 

 chemical reagents. How far the deepening of colour, fre- 

 quently observable when yellow lipochromes are treated 

 with solutions of caustic soda or potash, corresponds to 

 such a change, must also be left to be decided by further 

 investigation. In this connection it may be noted that 

 Courchet (2) separates the two lipochrome series named 

 above very widely, on the ground that the orange series 

 frequently occurs naturally in a crystalline condition, and 

 can be readily crystallised artificially, whereas the yellow 

 series is always amorphous. From his figures, however, 

 there seems some reason to believe that his orange crystals 

 were in part cholesterin, coloured with unaltered lipochrome, 

 and until we have extended and exact investigations on 

 the subject it seems better to regard the lipochromes as a 

 natural group. 



As to the meaning of the lipochromes in metabolism, 

 and their direct origin, we unfortunately, as yet, know 

 nothing. Eecently, Schrotter-Kristelli (16) has put for- 

 ward a hypothesis upon the subject, which has been 

 adopted and elaborated by Simroth (17). Schrotter- 



