CAROTINOIDS IN THE PHANEROGAMS 57 



established (Tammcs (1900), Gocrrig (1917)). True chromoplastids 

 are, in fact, present. 



The disappearance of chlorophyll from the leaves in the autumn is 

 alone sufficient evidence of vital changes taking place in the proto- 

 plasm. Viewing the phenomenon of autumn coloration, therefore, in 

 the light of what is now known regarding the yellow chromolipoids of 

 the chloroplastids the questions naturally raised, as recently pointed 

 out by Miss Goerrig (1917) are: (1) are the autumn pigments merely 

 the yellow carotinoids already present in the chloroplastids, (2) are 

 the natural carotinoids of the green plastids augmented or possibly 

 replaced by other yellow pigments which may be closely related but 

 still capable of being differentiated from the normal carotinoids, or (3) 

 are the autumn pigments entirely new substances which replace the 

 normal carotinoids, destroyed, perhaps, with the chlorophyll? In spite 

 of the fact that these questions have been studied by Miss Goerrig 

 (1917) and by Tswett (1908b) using the most modern methods, the 

 question of autumn coloration, at least with respect to the yellow 

 colors, is not yet entirely cleared up. One can apparently state defi- 

 nitely that the yellow colors are not due to entirely new pigments. 

 Whether the plastid carotinoids arc present unchanged or slightly 

 modified is not so certain. It is also uncertain to what extent yellow 

 pigments of an entirely foreign nature are present and what part they 

 play, if any, in the autumn coloration. 5 Tswett's and Miss Goerrig's 

 studies differ decidedly on this point. 



We know from Miss Wheldale's ( 1916) splendid monograph that 

 there is a large group of trees, shrubs and climbing plants in whose 

 leaves red anthocyanins form abundantly in the autumn. Some of 

 those mentioned by Miss Wheldale have been shown by certain inves- 

 tigators to contain carotinoids also. Other plants do not form anthor 

 cyanins in their foliage in the autumn. Miss Wheldale mentions a 

 number of the latter in which autumn carotinoids have not yet been 

 demonstrated. These three groups of plants, together with the names 

 of the investigators who have demonstrated carotinoids in the autumn 

 leaf, are summarized in Tables 1, 2 and 3. 



of the plastids and a retention of the osmotic pressure of the cell plasma. The latter 

 is recognized by the disappearance of the plastid pigments, the disintegration of the 

 protoplasm and the formation of brown, ivddish brown or black pigments as the result 

 of an oxidation of colorless, water-soluble rhronioyens. 



In isolated cases such as the yellow leaves of the osage orange (Mm-lnrn nuran- 

 tiaca) one no doubt finds an abundance of the characteristic yellow ilavones, morin and 

 maclaurin found in the wood of this plant (Kressmanu, 11)14) in addition to carotinoids 

 (Goerrig, 1917). 



