CAROTINOIDS IN THE PHANEROGAMS 65 



ficient to account for the divergence of the results on this point. This 

 possibility should be investigated. 



Carotinoids in Autumn, and Winter Reddening 



The winter reddening of leaves of the English ivy (Hedcra helix), 

 privet (Ligitstrum vulgare) and other evergreens, and also that of cer- 

 tain herbaceous plants like Sa.rifraga umbroxa, which retain their 

 leaves in winter, as well as the autumn reddening of the Rosaceae and 

 many other individuals of various plant orders is due to anthocyanin 

 formation. The chemistry of autumn and winter reddening, there- 

 fore, does not seem to fall within the scope of this monograph. How- 

 ever, from the investigations of Molisch (1902), Tswett (1911b), and 

 Monteverde and Lubimenko (1913b), carotinoids with an antho- 

 cyanin-like color are responsible in some cases for autumn and winter 

 reddening. 



Schimper (1885) first examined the red pigment in winter foliage of 

 various firs (Abies) and other conifers, such as Thuja ericoides, Thuja 

 standishi, and the common box tree (Buxus sempervirens) and found 

 it soluble in alcohol, benzene and CS 2 , and that it was extracted from 

 alcohol by the last named solvent. He also noticed the red pigment 

 in various parts of the plant of many varieties of aloes, e.g., Aloe ver- 

 rucosa, Courchet (1888) later investigated the properties of this red 

 pigment and concluded that it was different from carotin and other 

 pigments because it did not give the blue color reaction with con. 

 H 2 S0 4 . Molisch (1902) believed that he was dealing with the same 

 pigment when he found that the red plastids in winter-red foliage 

 leaves of many (26) varieties of aloe's responded, in part at least, to 

 his alkali crystallization method. The pigment crystallized in the 

 form of needles, platelets, prisms or little stars, with a garnet red or 

 yellowish brown color, and gave the usual reaction with con. H 2 SO 4 , 

 HNO :) , etc. Similar crystals were obtained even more abundantly in 

 the chromoplastids of several varieties of Selaginella. Molisch con- 

 cluded that the winter reddening of aloes and Selaginella is due in 

 part to a red carotin (carotinoid). 8 



Tswett (1911b) likewise has found a red carotinoid, undoubtedly the 

 same pigment, in the winter foliage of several plants. These are 

 enumerated in Table 3. He proposes the name thujorhordin for the 



Molisch found a similar, if not the same pigment, normally imbedded in a colorless 

 stroma in the common horsetail (Equiaetum arvense), the pigment itself having been 

 observed first by Schimper (1885). 



